Статті в журналах: "Photophysical Studies - Organic Molecules"

1

Ramamurthy, V., and J. V. Caspar. "Photophysical Studies of Organic Molecules Included Within Zeolites." Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals 211, no. 1 (January 1992): 211–26. http://dx.doi.org/10.1080/10587259208025822.

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2

Ramamurthy, V., D. F. Eaton, and J. V. Caspar. "Photochemical and photophysical studies of organic molecules included within zeolites." Accounts of Chemical Research 25, no. 7 (July 1992): 299–307. http://dx.doi.org/10.1021/ar00019a005.

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3

Mohan, Makesh, Srikala Pangannaya, M. N. Satyanarayan, and Darshak R. Trivedi. "Photophysical and electrochemical properties of organic molecules: Solvatochromic effect and DFT studies." Optical Materials 77 (March 2018): 211–20. http://dx.doi.org/10.1016/j.optmat.2018.01.031.

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4

RAMAMURTHY, V., D. F. EATON, and J. V. CASPAR. "ChemInform Abstract: Photochemical and Photophysical Studies of Organic Molecules Included within Zeolites." ChemInform 23, no. 41 (August 21, 2010): no. http://dx.doi.org/10.1002/chin.199241288.

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5

Kumari, Rekha, Anitha Varghese, Louis George, and Sudhakar Y. N. "Effect of solvent polarity on the photophysical properties of chalcone derivatives." RSC Advances 7, no. 39 (2017): 24204–14. http://dx.doi.org/10.1039/c7ra01705g.

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6

Golcs, Ádám, Bálint Árpád Ádám, Viola Horváth, Tünde Tóth, and Péter Huszthy. "Synthesis, Molecular Recognition Study and Liquid Membrane-Based Applications of Highly Lipophilic Enantiopure Acridino-Crown Ethers." Molecules 25, no. 11 (May 31, 2020): 2571. http://dx.doi.org/10.3390/molecules25112571.

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New highly lipophilic enantiopure crown ethers containing a heterocyclic unit have been synthesized. Phase transport, UV-Vis- and fluorescence spectrophotometric investigations as well as electrochemical studies on the complexation of the new macrocycles with several amine and amino acid derivatives were also carried out. Achiral amines were used for studying the structural preference of the new macrocycles. Among the studied structural features of the guest molecules, the intermolecular π-π interaction showed the most significant effect on complexation, which made the aralkylamine-type compounds the most preferable guest molecules. The studied liquid membrane-based applications and photophysical investigations showed appreciable enantiomeric recognition toward some aralkylamine model compounds with homochiral preferences. New crown ether derivatives (R,R)-2 and (S,S)-2 were successfully applied as enantioselective carrier and sensor molecules.

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7

Jin, Ruifa, Xiaofei Zhang та Wenmin Xiao. "Theoretical Studies of Photophysical Properties of D−π−A−π−D-Type Diketopyrrolopyrrole-Based Molecules for Organic Light-Emitting Diodes and Organic Solar Cells". Molecules 25, № 3 (4 лютого 2020): 667. http://dx.doi.org/10.3390/molecules25030667.

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A series of D–π–A diketopyrrolopyrrole(DPP)-based small molecules were designed for organic light-emitting diode(OLEDs) and organic solar cell(OSCs) applications. Applying the PBE0/6-31G(d,p) method, the ground state geometry and relevant electronic properties were investigated. The first excited singlet state geometry and the absorption and fluorescent spectra were simulated at the TD-PBE0/6-31G(d,p) level. The calculated results revealed that the photophysical properties were affected through the introduction of different end groups. Furthermore, the electronic transitions corresponding to absorption and emission exhibited an intramolecular charge transfer feature. Our results suggest that the designed molecules acted not only as luminescent for OLEDs, but also as donor materials in OSCs. Moreover, they can also be used as potential electron transfer materials for OLEDs and OSCs.

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8

Huang, Ping, Xingzi Zou, Zhiyun Xu, Yanting Lan, Lijuan Chen, Baohua Zhang, and Li Niu. "Studies on Annihilation and Coreactant Electrochemiluminescence of Thermally Activated Delayed Fluorescent Molecules in Organic Medium." Molecules 27, no. 21 (November 2, 2022): 7457. http://dx.doi.org/10.3390/molecules27217457.

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Very recently, there is a great research interest in electrochemiluminescence (ECL) featuring thermally activated delayed fluorescence (TADF) properties, i.e., TADF-ECL. It is appealing since the earlier reports in this topic well-confirmed that this strategy has a great potential in achieving all-exciton-harvesting ECL efficiency under electrochemical excitation, which is a breakthrough in the topic of organic ECL. However, organic phase electrochemistry and ECL studies surrounding TADF-ECL are still extremely rare. Especially, the ECL spectra of previous reported TADF emitters are still very different from their PL spectra. In this work, we systematically measure and discuss the liquid electrochemistry and ECL behavior of two typical TADF molecules in organic medium. Most importantly, we verify for the first time that the ECL spectra of them (coreactant ECL mode) are identical to their PL spectra counterparts, which confirms the effectiveness of TADF photophysical properties in the coreactant ECL mode in practice.

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9

Uznanski, P., J. Pecherz, and M. Kryszewski. "Photophysical studies of hydrophobically functionalized polyionene systems in aqueous solutions." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 2041–46. http://dx.doi.org/10.1139/v95-252.

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Complexes of polyionene and anionic dyes and surfactant were prepared by exchange reaction of counterions in the parent polymer. Fluorescence studies were conducted to observe some characteristic behaviour of these complexes in water Polyionenes with aromatic hydrocarbons adopt an open conformation and there is no evidence for interpolymer interactions. On the contrary, polyionenes with long aliphatic counterions easily form microdomains in aqueous solution due to hydrophobic interaction as evidenced by an increase in excimer emission. Microdomains have an interpolymer nature, as confirmed by measurements of energy transfer from naphthalene to pyrene moieties. Polyionenes with SDS counterions interact with external surfactant molecules and form polymer–surfactant aggregates. Electrostatic repulsions between aggregates dominate on hydrophobic interaction between polymer chains and are responsible for conformational changes. Keywords: hydrophobically modified polymers, surfactants, complexation, fluorescence, nonradiative energy transfer

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10

Lee, Sanghyuck, Chul Soon Park, and Hyeonseok Yoon. "Nanoparticulate Photoluminescent Probes for Bioimaging: Small Molecules and Polymers." International Journal of Molecular Sciences 23, no. 9 (April 29, 2022): 4949. http://dx.doi.org/10.3390/ijms23094949.

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Recent interest in research on photoluminescent molecules due to their unique properties has played an important role in advancing the bioimaging field. In particular, small molecules and organic dots as probes have great potential for the achievement of bioimaging because of their desirable properties. In this review, we provide an introduction of probes consisting of fluorescent small molecules and polymers that emit light across the ultraviolet and near-infrared wavelength ranges, along with a brief summary of the most recent techniques for bioimaging. Since photoluminescence probes emitting light in different ranges have different goals and targets, their respective strategies also differ. Diverse and novel strategies using photoluminescence probes against targets have gradually been introduced in the related literature. Among recent papers (published within the last 5 years) on the topic, we here concentrate on the photophysical properties and strategies for the design of molecular probes, with key examples of in vivo photoluminescence research for practical applications. More in-depth studies on these probes will provide key insights into how to control the molecular structure and size/shape of organic probes for expanded bioimaging research and applications.

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11

Tka, Najeh, Mohamed Adnene Hadj Ayed, Mourad Ben Braiek, Mahjoub Jabli, Noureddine Chaaben, Kamel Alimi, Stefan Jopp, and Peter Langer. "2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties." Beilstein Journal of Organic Chemistry 17 (July 16, 2021): 1629–40. http://dx.doi.org/10.3762/bjoc.17.115.

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Acridine derivatives have attracted considerable interest in numerous areas owing to their attractive physical and chemical properties. Herein, starting from readily available anthranilic acid, an efficient synthesis of 2,4-bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridine derivatives was accomplished via a one-pot double Sonogashira cross-coupling method. The UV-visible absorption and emission properties of the synthesized molecules have been examined. Additionally, theoretical studies based on density functional theory (DFT/B3LYP/6-31G(d)) were carried out.

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12

Jayaraj, Nithyanandhan, Steffen Jockusch, Lakshmi S. Kaanumalle, N. J. Turro, and V. Ramamurthy. "Dynamics of capsuleplex formed between octaacid and organic guest molecules — Photophysical techniques reveal the opening and closing of capsuleplex." Canadian Journal of Chemistry 89, no. 2 (February 2011): 203–13. http://dx.doi.org/10.1139/v10-104.

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This manuscript is concerned with the opening and closing of a capsuleplex made up of organic guest molecules and two cavitand molecules known as octaacid (OA). The capsuleplex is loosely held together in water through weak interactions. We have investigated the opening–closing of the OA capsuleplex by monitoring the quenching of excited singlet and (or) triplet states of nine different guest molecules encapsulated within a capsule by molecular oxygen that is dissolved in water surrounding the capsule. The rate constants for oxygen quenching of the excited guest molecules were estimated by monitoring the intensity of fluorescence/phosphorescence or lifetimes of excited states of guest molecules in the presence of different concentrations of oxygen in water. Guest molecules were chosen such that one could probe the opening–closing process during a time range of 0.05 to 922 µs. We believe that the oxygen quenching constant reflects the accessibility of oxygen to the guest enclosed within the OA capsuleplex, and this in turn depends on the capsule opening–closing rate constant. Based on the quenching studies, we conclude that guests whose lifetimes are shorter than 5 µs are inaccessible to oxygen. Results presented in this report suggest that the extent and time scale for opening depends on the guest.

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13

Zhou, Meng, Chenjie Zeng, Qi Li, Tatsuya Higaki, and Rongchao Jin. "Gold Nanoclusters: Bridging Gold Complexes and Plasmonic Nanoparticles in Photophysical Properties." Nanomaterials 9, no. 7 (June 28, 2019): 933. http://dx.doi.org/10.3390/nano9070933.

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Recent advances in the determination of crystal structures and studies of optical properties of gold nanoclusters in the size range from tens to hundreds of gold atoms have started to reveal the grand evolution from gold complexes to nanoclusters and further to plasmonic nanoparticles. However, a detailed comparison of their photophysical properties is still lacking. Here, we compared the excited state behaviors of gold complexes, nanolcusters, and plasmonic nanoparticles, as well as small organic molecules by choosing four typical examples including the Au10 complex, Au25 nanocluster (1 nm metal core), 13 diameter Au nanoparticles, and Rhodamine B. To compare their photophysical behaviors, we performed steady-state absorption, photoluminescence, and femtosecond transient absorption spectroscopic measurements. It was found that gold nanoclusters behave somewhat like small molecules, showing both rapid internal conversion (<1 ps) and long-lived excited state lifetime (about 100 ns). Unlike the nanocluster form in which metal–metal transitions dominate, gold complexes showed significant charge transfer between metal atoms and surface ligands. Plasmonic gold nanoparticles, on the other hand, had electrons being heated and cooled (~100 ps time scale) after photo-excitation, and the relaxation was dominated by electron–electron scattering, electron–phonon coupling, and energy dissipation. In both nanoclusters and plasmonic nanoparticles, one can observe coherent oscillations of the metal core, but with different fundamental origins. Overall, this work provides some benchmarking features for organic dye molecules, organometallic complexes, metal nanoclusters, and plasmonic nanoparticles.

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14

Ruiu, Andrea, Mireille Vonlanthen, Sandra M. Rojas-Montoya, Israel González-Méndez, and Ernesto Rivera. "Unusual Fluorescence Behavior of Pyrene-Amine Containing Dendrimers." Molecules 24, no. 22 (November 12, 2019): 4083. http://dx.doi.org/10.3390/molecules24224083.

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A new class of pyrene-based dendrimers, characterized by the presence of a 1,4,7,10-Tetraazacyclododecane (cyclen) unit as the core, was studied by SSF (steady-state fluorescence) and SPC (single-photon counting fluorescence). The photophysical behavior of these dendrimers was studied in THF, DMF and DMSO solution. The typical signals for pyrene-labeled molecules were recorded in each solvent, showing the representative fluorescence spectra: the corresponding emissions of monomer and excimer of the pyrene chromophore are observed. Unexpectedly, the typical quenching of tertiary amine on the pyrene emission was not observed in these dendrimers. Quenching studies were performed by adding up to 3 equivalents of trifluoroacetic acid (TFA). To our knowledge, this is the first report of pyrene’s unquenching behavior by a tertiary amine.

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15

Porcu, Pasquale, Mireille Vonlanthen, Israel González-Méndez, Andrea Ruiu, and Ernesto Rivera. "Design of Novel Pyrene-Bodipy Dyads: Synthesis, Characterization, Optical Properties, and FRET Studies." Molecules 23, no. 9 (September 7, 2018): 2289. http://dx.doi.org/10.3390/molecules23092289.

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A new series of dendronized bodipys containing pyrene units was synthesized and characterized. Their optical and photophysical properties were determined by absorption and fluorescence spectroscopy. This series includes three different compounds. The first one has an anisole group linked to the bodipy unit, which was used as the reference compound. In the second, the bodipy core is linked to a zero generation dendron with one pyrene unit. The third compound contains a first generation Fréchet-type dendron bearing two pyrene units. In this work, the combination pyrene-bodipy was selected as the donor-acceptor pair for this fluorescence resonance energy transfer (FRET) study. Doubtless, these two chromophores exhibit high quantum yields, high extinction coefficients, and both their excitation and emission wavelengths are located in the visible region. This report presents a FRET study of a novel series of pyrene-bodipy dendritic molecules bearing flexible spacers. We demonstrated via spectroscopic studies that FRET phenomena occur in these dyads.

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16

Fauvell, Thomas J., Zhengxu Cai, Matthew S. Kirschner, Waleed Helweh, Pyosang Kim, Tianyue Zheng, Richard D. Schaller, Luping Yu, and Lin X. Chen. "Effects of Intra- and Interchain Interactions on Exciton Dynamics of PTB7 Revealed by Model Oligomers." Molecules 25, no. 10 (May 23, 2020): 2441. http://dx.doi.org/10.3390/molecules25102441.

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Recent studies have shown that molecular aggregation structures in precursor solutions of organic photovoltaic (OPV) polymers have substantial influence on polymer film morphology, exciton and charge carrier transport dynamics, and hence, the resultant device performance. To distinguish photophysical impacts due to increasing π-conjugation from chain lengthening and π–π stacking from single/multi chain aggregation in solution and film, we used oligomers of a well-studied charge transfer polymer PTB7 with different lengths as models to reveal intrinsic photophysical properties of a conjugated segment in the absence of inter-segment aggregation. In comparison with previously studied photophysical properties in polymeric PTB7, we found that oligomer dynamics are dominated by a process of planarization of the conjugated backbone into a quinoidal structure that resembles the self-folded polymer and that, when its emission is isolated, this quinoidal excited state resembling the planar polymer chain exhibits substantial charge transfer character via solvent-dependent emission shifts. Furthermore, the oligomers distinctly lack the long-lived charge separated species characteristic of PTB7, suggesting that the progression from charge transfer character in isolated chains to exciton splitting in neat polymer solution is modulated by the interchain interactions enabled by self-folding.

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17

Mantur, Shivaraj, Mallikarjun Kalagouda Patil, Afra Quasar Abdul Rasheed Nadaf, Mahesh Sadashivappa Najare, Mohammed Yaseen, Aravind Raviraj Nesaragi, Sanjeev Ramchandra Inamdar, Imtiyaz Ahmed Khazi та Ravindra Ramappa Kamble. "Orange to red emissive aldehyde substituted donor-π-acceptor phenothiazine derivatives: Optoelectronic, DFT and thermal studies". European Journal of Chemistry 14, № 1 (31 березня 2023): 16–29. http://dx.doi.org/10.5155/eurjchem.14.1.16-29.2320.

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A new class of probes was synthesized using a simple and efficient synthetic protocol. These compounds (PTZ-6(a-e)) have the phenothiazine (PTZ) moiety as the electron donor (D) and substituted aldehydes along with the acrylonitrile group, which acts as the electron acceptor (A), thus making D-π-A push-pull system. The structures of the newly synthesized series of small organic target molecules PTZ-6(a-e) were investigated and confirmed by spectros-copic techniques. The optical/solvatochromic properties were studied in detail by UV-vis absorption and fluorescence spectroscopy, because the molecules have shown good solubility in organic solvents. The density functional theory (DFT) model with the CAM-B3LYP function is utilized to study the photophysical properties of the probes, as these probes exhibited orange-to-red emission. Optical band gap values ranged from 2.32 to 2.50 eV, and these probes exhibited good thermal stability with a melting temperature of 136 to 198 °C and a T5d temperature range from 335 to 354 °C. The cyclic voltammetry study confirms that the Eoxonset values of the target compounds are 0.80 eV. The quantum yields (Φ) of the probes are measured experimentally in ethanol and the Stokes shifts are observed to be in the range of 4846-9430 cm-1. The results displayed that novel (D-A-D) chromophores could play an important role in organic optoelectronics.

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18

Lifshits, Liubov M., Varun Singh, Matthias Zeller, and Jeremy K. Klosterman. "Ethyl 4-(9H-carbazol-9-yl)benzoate: fivefold superstructure with ten crystallographically independent molecules refined from a twinned crystal." Acta Crystallographica Section C Structural Chemistry 72, no. 11 (October 24, 2016): 901–9. http://dx.doi.org/10.1107/s2053229616015825.

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The photophysical properties of organic fluorophores are sensitive to the local sterics of the surrounding environment. Restriction of torsional motion in aggregates and crystals can give rise to enhanced emissive behavior.N-Aryl-substituted carbazoles serve an essential role as ubiquitous host matrices for organic light-emitting diodes, due to their large band gaps and high triplet energies, and so studies connecting photophysical behaviors with detailed crystallographic structural information are important. To elucidate the structural changes involved in the excited-state charge-transfer processes ofN-aryl-substituted carbazoles with ester withdrawing groups, ethyl 4-(9H-carbazol-9-yl) benzoate, C21H17NO2, was synthesized. The compound crystallizes with ten independent molecules in the asymmetric unit that pack together through moderate C—H...π interactions between carbazole units (2.5–2.9 Å) and π-stacks of benzoate groups (3.8–3.9 Å) between neighboring molecules. Four of the ten independent molecules show disorder by rotation of the ethyl carboxylate groups, with major occupancy rates between 0.931 (3) and 0.840 (3). The attached benzoate groups are also disordered, with identical occupancies, to compensate for the altered steric profile of the misaligned ethyl ester groups. For two molecules, the disorder extends to the entire carbazole units as well. Torsion angles between the nonplanar carbazole and benzoate groups range from θ = 44.8 to 57.2°, while those between the benzoate planes and the carboxylate COO atoms vary from α = 6.4 to 15.7°. The crystal is twinned by pseudomerohedry. The superstructure can be reduced to a hypothetical averaged parent structure in the space groupPbcnwithZ′ = 1, displaying fourfold disorder. Variable-temperature data collection shows that there is no phase transition between the disordered supercell and the hypothetical parent structure; supercell reflections persist up to 350 K. We propose that the disorder and variation in torsion angles result from frustrated close-packing and necessitate a unit cell with a highZ′ number.

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19

Mishra, Amaresh, Elena Mena-Osteritz, and Peter Bäuerle. "Synthesis, photophysical and electrochemical characterization of terpyridine-functionalized dendritic oligothiophenes and their Ru(II) complexes." Beilstein Journal of Organic Chemistry 9 (May 6, 2013): 866–76. http://dx.doi.org/10.3762/bjoc.9.100.

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Pd-catalyzed Sonogashira cross-coupling reactions were used to synthesize novel π-conjugated oligothienylene-ethynylene dendrons and their corresponding terpyridine-based ligands. Their complexation with Ru(II) led to interesting novel metallodendrimers with rich spectroscopic properties. All new compounds were fully characterized by 1H and 13C NMR, as well as MALDI–TOF mass spectra. Density functional theory (DFT) calculations performed on these complexes gave more insight into the molecular orbital distributions. Photophysical and electrochemical studies were carried out in order to elucidate structure–property relationships and the effect of the dendritic structure on the metal complexes. Photophysical studies of the complexes revealed broad absorption spectra covering from 250 to 600 nm and high molar extinction coefficients. The MLCT emission of these complexes were significantly red-shifted (up to 115 nm) compared to the parent [Ru(tpy)2]2+ complex.

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20

Khisamov, Radmir, Taisiya Sukhikh, Denis Bashirov, Alexey Ryadun, and Sergey Konchenko. "Structural and Photophysical Properties of 2,1,3-Benzothiadiazole-Based Phosph(III)azane and Its Complexes." Molecules 25, no. 10 (May 22, 2020): 2428. http://dx.doi.org/10.3390/molecules25102428.

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Here we describe the synthesis of a novel N,N’-bis(2,1,3-benzothiadiazol-4-yl)-1-phenylphosphanediamine (H2L) and its zinc (II) and copper (I) coordination compounds [Zn2L2]·nC7H8 (1·nC7H8), [Zn2(H2L)2Cl4]·nC7H8 (2·nC7H8), and [Cu(H2L)Cl]n·nTHF (3·THF). According to single crystal X-ray diffraction analysis, H2L ligand and its deprotonated species exhibit different coordination modes. An interesting isomerism is observed for the complexes [Zn2(H2L)2Cl4] (2a and 2b) that differ by the arrangement of H2L. Both complexes possess internal cavities capable of incorporating toluene molecules. Upon toluene release, the geometry of 2b changes substantially, while that of 2a changes slightly. Due to the diverse structures, the compounds 1–3 reveal different photophysical properties. These results are discussed based on previously reported studies and DFT (density functional theory) calculations.

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21

Ye, Chen, De-Shan Zhang, Bin Chen, Chen-Ho Tung, and Li-Zhu Wu. "Quantum dots: Another choice to sensitize organic transformations." Chemical Physics Reviews 4, no. 1 (March 2023): 011304. http://dx.doi.org/10.1063/5.0126893.

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Photochemical reactions are among the most important reactions in both theoretical studies and practical applications, since they utilize photon energy as the primary driving force. The sensitizer species is the key component connecting photons and the chemical materials of the reaction, which is conventionally among organic dyes or metal complex molecules. Semiconductor quantum dots (QDs), widely used in optoelectronic materials, and fluorescence sensing can be also applied to organic transformations due to their inherent physical and chemical properties. The similar functionalities and special photophysical features make QDs an ideal sensitizer and promote the efficient progress of the photochemical reactions. Moreover, the booming of QD photocatalysis reveals the excellent potential of interdisciplinary development between nano-materials science and organic chemistry QDs. Hence, a systematical explanation of the reaction principle of QDs in photocatalytic processes is necessary. In this review, we analyze the structural and optical properties of the QDs and illustrate how QDs participate in and facilitate organic reactions belonging to different pathways. We also present an outlook on the development of QD photocatalysis.

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22

Johnson, Darren W., Michael M. Haley, and Jeremy P. Bard. "Bumpy Roads Lead to Beautiful Places: The Twists and Turns in Developing a New Class of PN-Heterocycles." Synlett 31, no. 19 (July 13, 2020): 1862–77. http://dx.doi.org/10.1055/s-0040-1707168.

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The Haley and Johnson labs at the University of Oregon have been collaborating since 2006, combining skillsets in synthetic organic, physical organic, and supramolecular chemistries. This joint project has produced many examples of host molecules that bind anionic guests and give chemical, photophysical, and/or electrical responses. Many of these receptors utilize two-armed arylethynyl backbones that have a variety of hydrogen- or halogen-bonding functional groups appended. However, in attempts to produce a bisamide-containing host using a peptide-coupling protocol with P(OPh)3 present, we isolated something unexpected – a heterocycle containing neighboring P and N atoms. This ‘failed’ reaction turned into a surprisingly robust synthesis of phosphaquinolinones, an unusual class of PN-heterocycles. This Account article tells the rollercoaster story of these heterocycles in our lab. It will highlight our key works to this field, including a suite of fundamental studies of both the original PN-naphthalene moiety, as well as a variety of structural modifications to the arene backbone. It will also discuss the major step forward the project took when we developed a phosphaquinolinone-containing receptor molecule capable of binding HSO4 – selectively, reversibly, and with recyclability. With these findings, the project has gone from hospice care to making a full, robust recovery.1 Introduction2 Initial Discovery3 Setbacks Breathe New Life4 A New Dynamic Duo Develops Dozens of Derivatives5 Physicochemical Characterization5.1 Fluorescence5.2 Molecular Structures5.3 Solution Dimerization Studies6 Applying What We Have Learned6.1 Development of Supramolecular Host6.2 Use of PN Moiety as an Impressive Fluorophore7 Conclusions and Outlook

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23

Nowakowska, M., B. White, and J. E. Guillet. "Studies of the antenna effect in polymer molecules. 13. Preparation and photophysical studies of poly(sodium styrenesulfonate-co-2-vinylnaphthalene)." Macromolecules 22, no. 10 (October 1989): 3903–8. http://dx.doi.org/10.1021/ma00200a016.

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24

El-Shehawy, Ashraf A., Adel M. Attia, Abdul-Rahman IA Abdallah та Morad M. El-Hendawy. "Synthesis, characterization, photophysical properties, and computational studies on N-hexylphenothiazine/cyanopyridine based π-conjugated copolymers". High Performance Polymers 33, № 6 (28 січня 2021): 712–26. http://dx.doi.org/10.1177/0954008320988757.

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In this paper, π-conjugated copolymers, namely N-hexylphenothiazine/cyanopyridine/phenyl/benzothiadiazole, N-hexylphenothiazine/cyanopyridine/phenyl/9,9-dihexylfluorene, and N-hexylphenothiazine/cyanopyridine/phenyl/9,9-diethylhexylfluorene were readily synthesized via Pd-catalyzed Suzuki cross-coupling reaction. The polymer structures and their photophysical properties were characterized by elemental analysis, 1H NMR, GPC, TGA, XRD, UV-vis absorption and PL spectroscopy measurements. The coupling agent effect on photophysical properties of copolymers was investigated to rationally design polymers with particular physical properties to be employed in optoelectronic devices. The UV-vis absorption spectroscopy of copolymers showed λmax at a range of ∼334–474 nm and red-shifted in their films to a range of ∼342–381 nm. These copolymers displayed highly intense fluorescence in their solutions and films. The PL spectra of copolymers indicated red and near-infrared light, rendering them a prospect for being red and near-infrared light-emitting materials for PLEDs. XRD analysis demonstrated a d-spacing range of ∼3.79–4.32 Å, reflecting π-π stacking and some degree of crystallinity in some polymers, and only P1 and P2 showed peaks in the small-angle region, indicating lamellar structures. To understand the relationship between molecular structures of target materials and their photophysical and photovoltaic properties, density functional theory (DFT) and its time-dependent form (TD-DFT) were employed.

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25

Zhuang, Peifeng, Chang Yuan, Yunhao Bai, Changcheng He, Jiayu Long, Hongwei Tan, and Huiliang Wang. "Effects of Through-Bond and Through-Space Conjugations on the Photoluminescence of Small Aromatic and Aliphatic Aldimines." Molecules 27, no. 22 (November 19, 2022): 8046. http://dx.doi.org/10.3390/molecules27228046.

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Through-bond conjugation (TBC) and/or through-space conjugation (TSC) determine the photophysical properties of organic luminescent compounds. No systematic studies have been carried out to understand the transition from aromatic TBC to non-aromatic TSC on the photoluminescence of organic luminescent compounds. In this work, a series of small aromatic and aliphatic aldimines were synthesized. For the aromatic imines, surprisingly, N,1-diphenylmethanimine with the highest TBC is non-emissive, while N-benzyl-1-phenylmethanimine and N-cyclohexyl-1-phenylmethanimine emit bright fluorescence in aggregate states. The aliphatic imines are all emissive, and their maximum emission wavelength decreases while the quantum yield increases with a decrease in steric hindrance. The imines show concentration-dependent and excitation-dependent emissions. Theoretical calculations show that the TBC extents in the aromatic imines are not strong enough to induce photoluminescence in a single molecule state, while the intermolecular TSC becomes dominant for the fluorescence emissions of both aromatic and aliphatic imines in aggregate states, and the configurations and spatial conformations of the molecules in aggregate states play a key role in the formation of effective TSC. This study provides an understanding of how chemical and spatial structures affect the formation of TBC and TSC and their functions on the photoluminescence of organic luminescent materials.

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26

Chelike, Dinesh Kumar, Ananthan Alagumalai, Muthukumar V. R., Senthil A. Gurusamy Thangavelu, and Ananthanarayanan Krishnamoorthy. "Tunable yellow–green emitting cyclotriphosphazene appended phenothiazine hydrazone hybrid material: synthesis, characterisation, photophysical and electrochemical studies." New Journal of Chemistry 44, no. 31 (2020): 13401–14. http://dx.doi.org/10.1039/d0nj02976a.

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A novel tunable yellow–green emitting inorganic–organic luminescent hybrid molecule, CTP-PTZ, an assembly of six units of the PTZ hydrazone Schiff base on the periphery of inorganic heterocycle cyclotriphosphazene, is reported.

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27

Svetlichnyi, Valentin M., Elena L. Aleksandrova, Nadezda V. Matyushina, Lyudmila A. Myagkova, Tatyana N. Nekrasova, and Ruslan Yu Smyslov. "Molecular design of optoelectronic structures based on carbazole- and indolocarbazole-containing polyphenylquinolines." High Performance Polymers 29, no. 6 (May 4, 2017): 730–49. http://dx.doi.org/10.1177/0954008317706734.

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In this study, the molecular design of synthesized polymeric polyphenylquinoline (PPQ) structures is associated with the varying chemical nature of the bridging group ( X) between the phenylquinoline cycles and the heteroarylene radicals ( Ar) in the repeating unit of PPQs. The photophysical study of optical, photosensitive, and luminescent properties of the PPQs was carried out for isolated macromolecules in solution and interacting molecules in films while varying their intermolecular interactions for PPQ molecules in different matrices. The matrix isolation method we used made it possible to minimize intermacromolecular interactions whose enhancement in coatings leads to an efficient luminescence quenching. To separate the processes of intramolecular and intermacromolecular energy transfer, we studied the photoluminescence from mixtures of PPQ homopolymers. The analysis of ionization potentials for the molecular structures of Ar moieties ( IDAr) and a bridging group X ( IDX) of synthesized PPQs, as well as of copolymers containing carbazole and indolo[3,2-b]carbazole moieties, is given. This analysis based on the study of optical properties (absorption, photosensitivity, luminescence) and electrical characteristics for PPQ led to recommendations on PPQ promising structures for use in optoelectronic devices.

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28

Somasundaram, Sivaraman, Eswaran Kamaraj, Su Jin Hwang, Sooyoung Jung, Moon Gun Choi та Sanghyuk Park. "Synthesis, structural, and photophysical studies of π-fused acenaphtho[1,2- d ]imidazole-based excited-state intramolecular proton transfer molecules". Journal of Molecular Structure 1137 (червень 2017): 43–49. http://dx.doi.org/10.1016/j.molstruc.2017.02.025.

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29

Jia, Fuchao, Shuo Wang, Yan Man, Parveen Kumar, and Bo Liu. "Recent Developments in the Interactions of Classic Intercalated Ruthenium Compounds: [Ru(bpy)2dppz]2+ and [Ru(phen)2dppz]2+ with a DNA Molecule." Molecules 24, no. 4 (February 20, 2019): 769. http://dx.doi.org/10.3390/molecules24040769.

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[Ru(bpy)2dppz]2+ and [Ru(phen)2dppz]2+ as the light switches of the deoxyribose nucleic acid (DNA) molecule have attracted much attention and have become a powerful tool for exploring the structure of the DNA helix. Their interactions have been intensively studied because of the excellent photophysical and photochemical properties of ruthenium compounds. In this perspective, this review describes the recent developments in the interactions of these two classic intercalated compounds with a DNA helix. The mechanism of the molecular light switch effect and the selectivity of these two compounds to different forms of a DNA helix has been discussed. In addition, the specific binding modes between them have been discussed in detail, for a better understanding the mechanism of the light switch and the luminescence difference. Finally, recent studies of single molecule force spectroscopy have also been included so as to precisely interpret the kinetics, equilibrium constants, and the energy landscape during the process of the dynamic assembly of ligands into a single DNA helix.

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30

Martínez, Javier, Igor Osorio-Roman, and Andrés F. Gualdrón-Reyes. "Progress of Organic/Inorganic Luminescent Materials for Optical Wireless Communication Systems." Photonics 10, no. 6 (June 7, 2023): 659. http://dx.doi.org/10.3390/photonics10060659.

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The growing demand for faster data transference and communication allowed the development of faster and more efficient communication network-based technologies, with wider bandwidth capability, high resilience to electromagnetic radiation, and low latency for information travelling. To provide a suitable alternative to satisfy data transmission and consumption demand, wireless systems were established after a decade of studies on this topic. More recently, visible light communication (VLC) processes were incorporated as interesting wireless approaches that make use of a wide frequency communication spectrum to reach higher bandwidth values and accelerate the speed of data/information transmission. For this aim, light converters, such as phosphor materials, are reported to efficiently convert blue light into green, yellow, and red emissions; however, long carrier lifetimes are achieved to enlarge the frequency bandwidth, thereby delaying the data transference rate. In this review, we focused on recent advances using different luminescent materials based on prominent polymers, organic molecules, and semiconductor nanocrystals with improved photophysical properties and favored carrier recombination dynamics, which are suitable to enhance the VLC process. Here, the main features of the above materials are highlighted, providing a perspective on the use of luminescent systems for efficient optical communication applications.

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31

Golcs, Ádám, Korinna Kovács, Panna Vezse, Tünde Tóth, and Péter Huszthy. "Acridino-Diaza-20-Crown-6 Ethers: New Macrocyclic Hosts for Optochemical Metal Ion Sensing." Molecules 26, no. 13 (July 1, 2021): 4043. http://dx.doi.org/10.3390/molecules26134043.

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Acridino-diaza-20-crown-6 ether derivatives as new turn-on type fluorescent chemosensors with an excellent functionality and photophysical properties have been designed and synthesized for metal ion-selective optochemical sensing applications. Spectroscopic studies revealed that in an acetonitrile-based semi-aqueous medium, the sensor molecules exhibited a remarkable fluorescence enhancement with high sensitivity only toward Zn2+, Al3+ and Bi3+, among 23 different metal ions. Studies on complexation showed a great coordinating ability of logK > 4.7 with a 1:1 complex stoichiometry in each case. The detection limits were found to be from 59 nM to micromoles. The new ionophores enabled an optical response without being affected either by the pH in the range of 5.5–7.5, or the presence of various anions or competing metal ions. Varying the N-substituents of the new host-backbone provides diverse opportunities in both immobilization and practical applications without influencing the molecular recognition abilities.

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32

Nikol’skiy, Vladislav V., Mikhail E. Minyaev, Maxim A. Bastrakov, and Alexey M. Starosotnikov. "Nucleophilic Functionalization of 2-R-3-Nitropyridines as a Versatile Approach to Novel Fluorescent Molecules." Molecules 27, no. 17 (September 3, 2022): 5692. http://dx.doi.org/10.3390/molecules27175692.

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A number of new 2-methyl- and 2-arylvinyl-3-nitropyridines were synthesized and their reactions with thiols were studied. It was found that 3-NO2 tends to be selectively substituted under the action of sulfur nucleophiles in the presence of another nucleofuge in position 5. Correlations between the substitution pattern and regioselectivity as well as photophysical properties were established. Some synthesized compounds possessed a large Stokes shift.

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33

S.D. Gomes, Vanessa, Renato E.F. Boto, Paulo Almeida, Paulo J.G. Coutinho, Mário Rui Pereira, M. Sameiro T. Gonçalves, and Lucinda V. Reis. "Squaraine dyes as serum albumins probes: Synthesis, photophysical experiments and molecular docking studies." Bioorganic Chemistry 115 (October 2021): 105221. http://dx.doi.org/10.1016/j.bioorg.2021.105221.

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34

Sikorski, M., E. Sikorska, F. Wilkinson, and R. P. Steer. "Studies of the photophysics and spectroscopy of alloxazine and related compounds in solution and in the solid state." Canadian Journal of Chemistry 77, no. 4 (April 1, 1999): 472–80. http://dx.doi.org/10.1139/v99-076.

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The absorption and emission spectra and the fluorescence lifetimes and quantum yields of alloxazine and several of its N- and C- methyl-substituted derivatives, including two isoalloxazines, have been measured in a nonpolar solvent (1,2-dichloroethane), a polar aprotic solvent (acetonitrile), and a polar protic solvent (ethanol). The excited state decays are all single exponential, suggesting that only one emitting species is present in all cases. The spectroscopic data show that the emitting species is the π,π* electronic excited state corresponding to the ground state of the absorbing molecule; there is no evidence of excited state proton transfer for any of these solutes in any of the three solvents. The longer lifetimes and larger fluorescence quantum yields of the isoalloxazines compared with the alloxazines can be attributed exclusively to significantly slower rates of radiationless relaxation in the excited isoalloxazines. The remission and emission spectra of these same compounds adsorbed on cellulose are similar to the corresponding absorption and emission spectra in homogeneous solution, suggesting that the emitting species are the same in the adsorbed state as they are in homogeneous solution. However, the adsorbed excited species exhibit non-exponential temporal decay, attributed to inhomogeneities in the binding of the chromophore to cellulose. The emission spectra of polycrystalline samples of alloxazine and lumichrome suggest the possible occurrence of double intermolecular excited state proton transfer, but this interpretation is not supported by the further photophysical data obtained here.Key words: photophysics, spectroscopy, alloxazine, lumiflavin, cellulose.

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35

Maragani, Ramesh, and Rajneesh Misra. "Ferrocenyl substituted triphenylamine based donor–acceptor molecular systems; synthesis, photophysical, electrochemical, and theoretical studies." Tetrahedron 70, no. 21 (May 2014): 3390–99. http://dx.doi.org/10.1016/j.tet.2014.03.096.

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36

Tzeliou, Christina Eleftheria, and Demeter Tzeli. "Metallocene-Naphthalimide Derivatives: The Effect of Geometry, DFT Methodology, and Transition Metals on Absorption Spectra." Molecules 28, no. 8 (April 19, 2023): 3565. http://dx.doi.org/10.3390/molecules28083565.

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In the present paper, the photophysical properties of metallocene-4-amino-1,8-naphthalimide-piperazine molecules (1-M2+), as well as their oxidized and protonated derivatives (1−M3+, 1-M2+-H+, and 1-M3+-H+), where M = Fe, Co, and Ni, were studied via DFT and TD-DFT, employing three functionals, i.e., PBE0, TPSSh, and wB97XD. The effect of the substitution of the transition metal M on their oxidation state, and/or the protonation of the molecules, was investigated. The present calculated systems have not been investigated before and, except for the data regarding their photophysical properties, the present study provides important information regarding the effect of geometry and of DFT methodology on absorption spectra. It was found that small differences in geometry, specifically in the geometry of N atoms, reflect significant differences in absorption spectra. The common differences in spectra due to the use of different functionals can be significantly increased when the functionals predict minima even with small geometry differences. For most of the calculated molecules, the main absorption peaks in visible and near-UV areas correspond mainly to charge transfer excitations. The Fe complexes present larger oxidation energies at 5.4 eV, whereas Co and Ni complexes have smaller ones, at about 3.5 eV. There are many intense UV absorption peaks with excitation energies similar to their oxidation energies, showing that the emission from these excited states can be antagonistic to their oxidation. Regarding the use of functionals, the inclusion of dispersion corrections does not affect the geometry, and consequently the absorption spectra, of the present calculated molecular systems. For certain applications, where there is a need for a redox molecular system including metallocene, the oxidation energies could be lowered significantly, to about 40%, with the replacement of the iron with cobalt or nickel. Finally, the present molecular system, using cobalt as the transition metal, has the potential to be used as a sensor.

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37

Payne, Liam, Jason D. Josephson, R. Scott Murphy, and Brian D. Wagner. "Photophysical Properties of Donor-Acceptor Stenhouse Adducts and Their Inclusion Complexes with Cyclodextrins and Cucurbit[7]uril." Molecules 25, no. 21 (October 24, 2020): 4928. http://dx.doi.org/10.3390/molecules25214928.

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Donor-acceptor Stenhouse adducts (DASAs) are a novel class of solvatochromic photoswitches with increasing importance in photochemistry. Known for their reversibility between open triene and closed cyclized states, these push-pull molecules are applicable in a suite of light-controlled applications. Recent works have sought to understand the DASA photoswitching mechanism and reactive state, as DASAs are vulnerable to irreversible “dark switching” in polar protic solvents. Despite the utility of fluorescence spectroscopy for providing information regarding the electronic structure of organic compounds and gaining mechanistic insight, there have been few studies of DASA fluorescence. Herein, we characterize various photophysical properties of two common DASAs based on Meldrum’s acid and dimethylbarbituric acid by fluorescence spectroscopy. This approach is applied in tandem with complexation by cyclodextrins and cucurbiturils to reveal the zwitterionic charge separation of these photoswitches in aqueous solution and the protective nature of supramolecular complexation against degradative dark switching. DASA-M, for example, was found to form a weak host-guest inclusion complex with (2-hydroxypropyl)-γ-cyclodextrin, with a binding constant K = 60 M−1, but a very strong inclusion complex with cucurbit[7]uril, with K = 27,000 M−1. This complexation within the host cavity was found to increase the half-life of both DASAs in aqueous solution, indicating the significant and potentially useful stabilization of these DASAs by host encapsulation.

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38

Li, Wenjing, Qi Wang, Yongshan Ma, Tianyi Jiang, Yanyan Zhu, Yuanyuan Shao, Cuizhen Sun, and Junsen Wu. "Photophysical property, electronic structure and solid-state packing of O-heterocyclic annulated perylene diimide." Pigment & Resin Technology 48, no. 3 (May 7, 2019): 256–62. http://dx.doi.org/10.1108/prt-04-2018-0034.

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PurposeSelf-organization has been regarded as a tool for the synthesis of well-defined organic nanostructures. Heterocyclic annulated perylene diimides are the subjects of considerable current research studies. The purpose of this study is to reveal the photophysical property, electronic structure and solid-state packing of O-heterocyclic annulated perylene diimide.Design/methodology/approachAsymmetrically five-membered O-heterocyclic annulated perylene diimide (OAPDI) was synthesized. Structure and purity of OAPDI were confirmed by1H NMR,13C NMR, IR and mass spectral techniques. Photophysical properties of OAPDI were studied using UV–vis absorption and fluorescence in both solution (CHCl3) and solid state. Scanning electron microscopic and atomic force microscopy were used to characterize the surface morphology of OAPDI. Conducting properties of the OAPDI were evaluated by current–voltage measurements. The compounds geometries were also optimized at 6-31G* using density functional theory.FindingsThe UV–vis absorption and fluorescence spectra of OAPDI in solution are blue-shifted in comparison with that of unsubstituted perylene bisimide. Solid-state UV–vis measurements of OAPDI indicate that it is capable of forming highly ordered structure. The non-covalent interactions, electrostatic attraction and p-p stacking moieties of OAPDI synergistically guide assembly and domain growth while maintaining the interpenetrating network of nanofibers in the solid film. The OAPDI gave higher current at −2.0 V (0.68µA) and 4.0 V (1.0µA).Originality/valueThis study will be helpful for exploring feasible routes to acquire soluble perylene diimides and well-defined organic nanostructures. Furthermore, such molecular tailoring approach would be helpful for designing and synthesizing novel organic semiconductive materials with excellent charge-transporting and light-emitting capabilities.

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39

Kubheka, Gugu, John Mack, Tebello Nyokong, and Zhen Shen. "NIR Absorbing AzaBODIPY Dyes for pH Sensing." Molecules 25, no. 16 (August 13, 2020): 3689. http://dx.doi.org/10.3390/molecules25163689.

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Two near-infrared (NIR) absorbing di(thien-2-nyl)-di(dimethylanilino)azaBODIPY dyes 2a and 2b were synthesized and characterized that differ depending on whether the dimethylaniline substituents are introduced at the 3,5- or 1,7-positions of the azaBODIPY core. The main spectral bands lie at 824 and 790 nm, respectively, in CH2Cl2. The effect of substituent position on the photophysical and pH sensing properties was analyzed through a comparison of the optical properties with the results of time-dependent density functional theory (TD-DFT) calculations. Protonation of the dimethylamino nitrogen atoms eliminates the intramolecular charge transfer properties of these compounds, and this results in a marked blue-shift of the main absorption bands to 696 and 730 nm, respectively, in CH2Cl2, and a fluorescence “turn-on” effect in the NIR region. The pH dependence studies reveal that the pKa values of the non-protonated 2a and 2b molecules are ca. 6.9 (±0.05) and 7.3 (±0.05), respectively, while that of the monoprotonated species for both dyes is ca. 1.4 (±0.05) making them potentially suitable for use as colorimetric pH indicators under highly acidic conditions.

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40

Chmovzh, Timofey N., Timofey A. Kudryashev, Karim S. Gaisin, and Oleg A. Rakitin. "4,7-Di(9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine." Molbank 2022, no. 3 (August 17, 2022): M1428. http://dx.doi.org/10.3390/m1428.

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Donor–acceptor–donor (D–A–D)-type molecules are considered as a promising class of NIR fluorescence materials. In this communication, 4,7-di(9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine was obtained by dehydrogenation of 4,7-bis(1,2,3,4,4a,9a-hexahydro-9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in toluene. The structure of the synthesized compound was established by elemental analysis; high-resolution mass spectrometry; 1H, 13C NMR, IR, and UV spectroscopy; and mass spectrometry. The photophysical properties of the title compound were studied and compared with spectral data of the [1,2,5]thiadiazolo[3,4-d]pyridazine analogue.

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41

Maroń, Anna Maria, Oliviero Cannelli, Etienne Christophe Socie, Piotr Lodowski, and Barbara Machura. "Push-Pull Effect of Terpyridine Substituted by Triphenylamine Motive—Impact of Viscosity, Polarity and Protonation on Molecular Optical Properties." Molecules 27, no. 20 (October 20, 2022): 7071. http://dx.doi.org/10.3390/molecules27207071.

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The introduction of an electron-donating triphenylamine motive into a 2,2′,6′,2′′-terpyridine (terpy) moiety, a cornerstone molecular unit in coordination chemistry, opens new ways for a rational design of photophysical properties of organic and inorganic compounds. A push-pull compound, 4′-(4-(di(4-tert-butylphenyl)amine)phenyl)-2,2′,6′,2′′-terpyridine (tBuTPAterpy), was thoroughly investigated with the use of steady-state and time-resolved spectroscopies and Density Functional Theory (DFT) calculations. Our results demonstrate that solvent parameters have an enormous influence on the optical properties of this molecule, acting as knobs for external control of its photophysics. The Intramolecular Charge Transfer (ICT) process introduces a remarkable solvent polarity effect on the emission spectra without affecting the lowest absorption band, as confirmed by DFT simulations, including solvation effects. The calculations ascribe the lowest absorption transitions to two singlet ICT excited states, S1 and S2, with S1 having several orders of magnitude higher oscillator strength than the “dark” S2 state. Temperature and viscosity investigations suggest the existence of two emitting excited states with different structural conformations. The phosphorescence emission band observed at 77 K is assigned to a localized 3terpy state. Finally, protonation studies show that tBuTPAterpy undergoes a reversible process, making it a promising probe of the pH level in the context of acidity determination.

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42

Efremova, Mariia M., Anastasia I. Govdi, Valeria V. Frolova, Andrey M. Rumyantsev, and Irina A. Balova. "Design and Synthesis of New 5-aryl-4-Arylethynyl-1H-1,2,3-triazoles with Valuable Photophysical and Biological Properties." Molecules 26, no. 9 (May 10, 2021): 2801. http://dx.doi.org/10.3390/molecules26092801.

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Cu-catalyzed 1,3-dipolar cycloaddition of methyl 2-azidoacetate to iodobuta-1,3-diynes and subsequent Suzuki-Miyaura cross-coupling were used to synthesize new triazoles derivatives: 5-aryl-4-arylethynyl-1H-1,2,3-triazoles. Investigation of their optical properties by using UV absorption and fluorescence emission spectroscopies revealed that all molecules possess fluorescence properties with the values of the Stokes shift more than 100 nm. The photophysical behavior of the two most promising triazoles in polar and non-polar solvents was also studied.

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43

Lee, Sam, and Mitchell A. Winnik. "Photophysical behavior of oligoethylene glycols labeled with naphthalene carboxylate and phosphate esters." Canadian Journal of Chemistry 72, no. 6 (June 1, 1994): 1587–95. http://dx.doi.org/10.1139/v94-198.

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The fluorescence spectra of tri- and tetraethylene glycol esterified with 2-(1-naphthyl)ethyl ethyl phosphate and 2-(1-naphthyl)ethyl 2-(ethoxy)ethyl phosphate were studied in dilute solutions of tetrahydrofuran (THF) and diethyl ether. They were compared with the fluorescence from tri- and tetraethylene glycol esterified with 1-naphthyl acetic acid. These compounds form intramolecular excimers. The extent of excimer formation is not extensive, but the relative amount of excimer emission from these compounds varies with the choice of solvent. Three synthetic intermediates to the phosphates, the 2-(1-naphthyl)ethyl N, N-diisopropylphosphoramidites of tri- and tetraethylene glycol and of 2-ethoxyethanol, were also examined. These compounds form intramolecular exciplexes. In THF, the relative amount of exciplex emission from the phosphoramidites follows the same trend as the carboxylate esters. In diethyl ether, the trend is different. Rates of fluorescence decay have been measured for these compounds. The results are discussed in terms of how information about the conformational and dynamic behavior of these molecules in solution can be obtained, and how the solvent can influence the relative amounts of excimer or exciplex fluorescence

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44

Shibu, Abhishek, Camilla Middleton, Carly O. Kwiatkowski, Meesha Kaushal, Jonathan H. Gillen, and Michael G. Walter. "Self-Assembly-Directed Exciton Diffusion in Solution-Processable Metalloporphyrin Thin Films." Molecules 27, no. 1 (December 22, 2021): 35. http://dx.doi.org/10.3390/molecules27010035.

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The study of excited-state energy diffusion has had an important impact in the development and optimization of organic electronics. For instance, optimizing excited-state energy migration in the photoactive layer in an organic solar cell device has been shown to yield efficient solar energy conversion. Despite the crucial role that energy migration plays in molecular electronic device physics, there is still a great deal to be explored to establish how molecular orientation impacts energy diffusion mechanisms. In this work, we have synthesized a new library of solution-processable, Zn (alkoxycarbonyl)phenylporphyrins containing butyl (ZnTCB4PP), hexyl (ZnTCH4PP), 2-ethylhexyl (ZnTCEH4PP), and octyl (ZnTCO4PP) alkoxycarbonyl groups. We establish that, by varying the length of the peripheral alkyl chains on the metalloporphyrin macrocycle, preferential orientation and molecular self-assembly is observed in solution-processed thin films. The resultant arrangement of molecules consequently affects the electronic and photophysical characteristics of the metalloporphyrin thin films. The various molecular arrangements in the porphyrin thin films and their resultant impact were determined using UV-Vis absorption spectroscopy, steady-state and time-resolved fluorescence emission lifetimes, and X-ray diffraction in thin films. The films were doped with C60 quencher molecules and the change in fluorescence was measured to derive a relative quenching efficiency. Using emission decay, relative quenching efficiency, and dopant volume fraction as input, insights on exciton diffusion coefficient and exciton diffusion lengths were obtained from a Monte Carlo simulation. The octyl derivative (ZnTCO4PP) showed the strongest relative fluorescence quenching and, therefore, the highest exciton diffusion coefficient (5.29 × 10−3 cm2 s−1) and longest exciton diffusion length (~81 nm). The octyl derivative also showed the strongest out-of-plane stacking among the metalloporphyrins studied. This work demonstrates how molecular self-assembly can be used to modulate and direct exciton diffusion in solution-processable metalloporphyrin thin films engineered for optoelectronic and photonic applications.

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45

Korzec, Mateusz, Sonia Kotowicz, Katarzyna Malarz, and Anna Mrozek-Wilczkiewicz. "Spectroscopic and Biological Properties of the 3-Imino-1,8-naphthalimide Derivatives as Fluorophores for Cellular Imaging." Molecules 28, no. 17 (August 25, 2023): 6255. http://dx.doi.org/10.3390/molecules28176255.

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This paper presents the photophysical and biological properties of eight 3-imino-1,8-naphthalimides. The optical properties of the compounds were investigated in the solvents that differed in their polarity (dichloromethane, acetonitrile, and methanol), including three methods of sample preparation using different pre-dissolving solvents such as dimethyl sulfoxide or chloroform. In the course of the research, it was found that there are strong interactions between the tested compounds and DMSO, which was visible as a change in the maximum emission band (λem) of the neat 3-imino-1,8-naphthalimides (λem = 470–480 nm) and between the compounds and DMSO (λem = 504–514 nm). The shift of the emission maximum that was associated with the presence of a small amount of DMSO in the sample was as much as 41 nm. In addition, the susceptibility of imines to hydrolysis in the methanol/water mixture with increasing water content and in the methanol/water mixture (v/v; 1:1) in the pH range from 1 to 12 was discussed. The studies showed that the compounds are hydrolysed in the CH3OH/H2O system in an acidic environment (pH in the range of 1 to 4). In addition, it was found that partial hydrolysis occurs in systems with an increased amount of water, and its degree may depend on the type of substituent on the imine bond. The compounds tended to quench the emission (ACQ) in the aggregated state and increase the emission related to the protonation of the imine bond. Moreover, it was found that the substituent in the imine bonds influenced a compound’s individual photophysical properties. Biological tests, including cytotoxicity studies and cellular localisation, were also performed for all of the molecules. All of the tested compounds exhibited green fluorescence in the MCF-7 cells and showed co-localisation in the mitochondria, endoplasmic reticulum, and lysosome. The obtained photophysical and biological results indicate the promising potential use of the tested compounds as cellular dyes.

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46

Bao, Yinyin. "Controlling Molecular Aggregation-Induced Emission by Controlled Polymerization." Molecules 26, no. 20 (October 16, 2021): 6267. http://dx.doi.org/10.3390/molecules26206267.

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In last twenty years, the significant development of AIE materials has been witnessed. A number of small molecules, polymers and composites with AIE activity have been synthesized, with some of these exhibiting great potential in optoelectronics and biomedical applications. Compared to AIE small molecules, macromolecular systems—especially well-defined AIE polymers—have been studied relatively less. Controlled polymerization methods provide the efficient synthesis of well-defined AIE polymers with varied monomers, tunable chain lengths and narrow dispersity. In particular, the preparation of single-fluorophore polymers through AIE molecule-initiated polymerization enables the systematic investigation of the structure–property relationships of AIE polymeric systems. Here, the main polymerization techniques involved in these polymers are summarized and the key parameters that affect their photophysical properties are analyzed. The author endeavored to collect meaningful information from the descriptions of AIE polymer systems in the literature, to find connections by comparing different representative examples, and hopes eventually to provide a set of general guidelines for AIE polymer design, along with personal perspectives on the direction of future research.

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Zammit, Ramon, Maria Pappova, Esther Zammit, John Gabarretta, and David C. Magri. "1,3,5-Triarylpyrazolines — pH-driven off-on-off molecular logic devices based on a “receptor1-fluorophore-spacer-receptor2” format with internal charge transfer (ICT) and photoinduced electron transfer (PET) mechanisms." Canadian Journal of Chemistry 93, no. 2 (February 2015): 199–206. http://dx.doi.org/10.1139/cjc-2014-0266.

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The excited state photophysical properties of the 1,3,5-triarylpyrazolines 1–4 were studied in methanol and 1:1 (v/v) methanol–water, as well as 1:4 (v/v) methanol–water and water by fluorescence spectroscopy. The molecules 2–4 incorporate a “receptor1-fluorophore-spacer-receptor2” format while 1 is a reference compound based on a “fluorophore-receptor1” design. The molecular probes operate according to photoinduced electron transfer (PET) and internal charge transfer (ICT) processes. At basic and neutral pHs, 2–4 are essentially nonfluorescent due to PET from the electron-donating dimethylamino moiety appended on the 5-phenyl ring to the excited state of the 1,3,5-triarylpyrazoline fluorophore. At proton concentrations of 10−3 mol/L, the dimethylamino unit is protonated resulting in a strong blue fluorescence about 460 nm with significant quantum yields up to 0.54. At acid concentrations above 10−2 mol/L, fluorescence quenching is observed by an ICT mechanism due to protonation of the pyrazoline chromophore. Symmetrical off-on-off fluorescence–pH profiles are observed, spanning six log units with a narrow on window within three pH units. Hence, 2–4 are novel examples of ternary photonic pH sensing molecular devices.

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48

Yoon, Dong I., Donald C. Selmarten, Hong Lu, Hui-Jean Liu, Carolyn Mottley, Mark A. Ratner, and Joseph T. Hupp. "Spectroscopic and photophysical studies of apparent cluster-to-organic-acceptor charge transfer in a molecular cadmium sulfide assembly." Chemical Physics Letters 251, no. 1-2 (March 1996): 84–89. http://dx.doi.org/10.1016/0009-2614(96)00046-2.

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49

Erzunov, Dmitry, Svetlana Tonkova, Anastasia Belikova, and Arthur Vashurin. "Enhanced Visible Light Absorption and Photophysical Features of Novel Isomeric Magnesium Phthalocyaninates with Cyanophenoxy Substitution." Chemosensors 10, no. 12 (November 28, 2022): 503. http://dx.doi.org/10.3390/chemosensors10120503.

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Novel metal-free and Mg(II) [3/4-(3,4-dicyanophenoxy)phenoxy]-substituted phthalocyanines were obtained and characterized using NMR, IR, UV-vis spectroscopy, and mass spectrometry. This substitution provided compounds with good solubility in organic media, and thus their spectroscopic and fluorescent properties were studied. The formation of the investigated phthalocyanine complexes with central magnesium ions led to the stabilization of macrocyclic molecules in solution, preventing aggregation through specific and universal solvation. From meta-substitution to para-substitution, insignificant spectroscopic changes were observed. The complexes exhibited higher values of molar light absorption coefficients and fluorescence quantum yields (up to 55%) compared to ligands. The efficiency of both the fluorescence-quenching and singlet oxygen generation processes in the case of magnesium [3/4-(3,4-dicyanophenoxy)phenoxy]phthalocyaninates was found to exceed that of the unsubstituted zinc phthalocyaninate, which suggests the potential applicability of these compounds as PDT sensitizers.

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50

Job, Nisha, Venkatesan S. Thimmakondu, and Krishnan Thirumoorthy. "In Silico Drug Design and Analysis of Dual Amyloid-Beta and Tau Protein-Aggregation Inhibitors for Alzheimer’s Disease Treatment." Molecules 28, no. 3 (February 1, 2023): 1388. http://dx.doi.org/10.3390/molecules28031388.

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Alzheimer’s disease (AD) is a progressive and irreversible neurodegenerative disorder that gradually leads to the state of dementia. The main features of AD include the deposition of amyloid-beta peptides (Aβ), forming senile plaques, and the development of neurofibrillary tangles due to the accumulation of hyperphosphorylated Tau protein (p-tau) within the brain cells. In this report, seven dual-inhibitor molecules (L1–7) that can prevent the aggregation of both Aβ and p-tau are suggested. The drug-like features and identification of the target proteins are analyzed by the in silico method. L1–7 show positive results in both Blood–Brain Barrier (BBB) crossing and gastrointestinal absorption, rendering to the results of the permeation method. The molecular docking test performed for L1–7 shows binding energies in the range of −4.9 to −6.0 kcal/mol towards Aβ, and −4.6 to −5.6 kcal/mol for p-tau. The drug’s effectiveness under physiological conditions is assessed by the use of solvation models on the investigated systems. Further, the photophysical properties of L1–3 are predicted using TD-DFT studies.

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