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Articles de revues sur le sujet « Homochiral complex »

Auteur : Grafiati
Publié le 21 décembre 2024

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1

Liu, Yu-Ling, Jia-Zhen Ge, Zhong-Xia Wang et Ren-Gen Xiong. « Metal–organic ferroelectric complexes : enantiomer directional induction achieved above-room-temperature homochiral molecular ferroelectrics ». Inorganic Chemistry Frontiers 7, no 1 (2020) : 128–33. http://dx.doi.org/10.1039/c9qi01197h.

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Colquhoun, Howard M., C. Timothy Powell, Zhixue Zhu, Christine J. Cardin, Yu Gan, Paula Tootell, Josephine S. W. Tsang et Neil M. Boag. « Enantiospecific Assembly of a Homochiral, Hexanuclear Palladium Complex ». European Journal of Inorganic Chemistry 2009, no 8 (mars 2009) : 999–1002. http://dx.doi.org/10.1002/ejic.200801045.

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3

Jiao, Luyang, Mengying Du, Yameng Hou, Yuan Ma et Xianglei Kong. « Homochiral or Heterochiral : A Systematic Study of Threonine Clusters Using a FT ICR Mass Spectrometer ». Symmetry 14, no 1 (6 janvier 2022) : 86. http://dx.doi.org/10.3390/sym14010086.

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The strong chiral preferences of some magic clusters of amino acids have attracted continually increasing interests due to their unique structures, properties and possible roles in homochirogenesis. However, how chirality can influence the generation and stability of cluster ions in a wild range of cluster sizes is still unknown for most amino acids. In this study, the preference for threonine clusters to form homochiral and heterochiral complex ions has been investigated by electrospray ionization (ESI) mass spectrometry. Abundant cluster [Thrn+mH]m+ ions (7 ≤ n ≤ 78, 1 ≤ m ≤ 5) have been observed for both samples of enantiopure (100% L) and racemic (50:50 L:D) threonine solutions. Further analyses of the spectra show that the [Thr14+2H]2+ ion is characterized by its most outstanding homochiral preference, and [Thr7+H]+ and [Thr8+H]+ ions also clearly exhibit their homochiral preferences. Although most of the triply charged clusters (20 ≤ n ≤ 36) are characterized by heterochiral preferences, the quadruply charged [Thrn+4H]4+ ions (40 ≤ n ≤ 59) have no obvious chiral preference in general. On the other hand, a weak homochiral preference exists for most of the quintuply charged ions observed in the experiment.
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Rose-Munch, Françoise, Vanessa Gagliardini, Anne Perrotey, Jean-Philippe Tranchier, Eric Rose, Pierre Mangeney, Alexandre Alexakis, Tonis Kanger et Jacqueline Vaissermann. « Two-step synthesis of homochiral monoaminals of tricarbonylphthalaldehydechromium complex ». Chemical Communications, no 20 (1999) : 2061–62. http://dx.doi.org/10.1039/a906043j.

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Fu, Da-Wei, Yu-Mei Song, Guo-Xi Wang, Qiong Ye, Ren-Gen Xiong, Tomoyuki Akutagawa, Takayoshi Nakamura, Philip Wai Hong Chan et Songping D. Huang. « Dielectric Anisotropy of a Homochiral Trinuclear Nickel(II) Complex ». Journal of the American Chemical Society 129, no 17 (mai 2007) : 5346–47. http://dx.doi.org/10.1021/ja0701816.

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Zhang, Qichun, Xianhui Bu, Zhien Lin, Maurizio Biasini, W. P. Beyermann et Pingyun Feng. « Metal-Complex-Decorated Homochiral Heterobimetallic Telluride Single-Stranded Helix ». Inorganic Chemistry 46, no 18 (septembre 2007) : 7262–64. http://dx.doi.org/10.1021/ic701135h.

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Zhang, Jing, Wen Li, Weifeng Bu, Lixin Wu, Ling Ye et Guangdi Yang. « The homochiral metallosupramolecular column structure of rhenium (I) complex ». Inorganica Chimica Acta 358, no 4 (mars 2005) : 964–70. http://dx.doi.org/10.1016/j.ica.2004.11.039.

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Wang, Guo-Xi, Guang-Fan Han, Qiong Ye, Ren-Gen Xiong, Tomoyuki Akutagawa, Takayoshi Nakamura, Philip Wai Hong Chan et Songping D. Huang. « Dielectric anisotropy of a homochiral rare-earth metal complex ». Dalton Transactions, no 19 (2008) : 2527. http://dx.doi.org/10.1039/b719580j.

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Bhattacharyya, Anik, Biswa Nath Ghosh, Santiago Herrero, Kari Rissanen, Reyes Jiménez-Aparicio et Shouvik Chattopadhyay. « Formation of a novel ferromagnetic end-to-end cyanate bridged homochiral helical copper(ii) Schiff base complex via spontaneous symmetry breaking ». Dalton Transactions 44, no 2 (2015) : 493–97. http://dx.doi.org/10.1039/c4dt03166k.

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Roithová, Jana. « Diastereoisomeric proton-bound complexes of 1,5-diaza-cis-decalin in the gas phase ». Collection of Czechoslovak Chemical Communications 74, no 2 (2009) : 243–54. http://dx.doi.org/10.1135/cccc2008185.

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Diastereoisomeric proton-bound complexes of 1,5-diaza-cis-decalin (1) with butan-2-amine (2) are studied by means of the DFT calculations and mass spectrometry. The calculations reveal that 2 is bound via proton to only one nitrogen atom of the bicyclic base 1. The homochiral complex is favored by about 4 kJ/mol over the heterochiral complex. For a more loosely bound ion-pair complex [(1H)I(2H)]+ of the protonated bases 1 and 2 with an iodine counterion the energy difference drops to about 2 kJ/mol. Chiral effects in the formation of [(1)H(2)]+ are studied by the collision-induced dissociation of [(1H)I(2H)]+ generated by the electrospray ionization of the solution of [1·Cu(OH)I] and 2 in acetonitrile. The dominant fragmentation of [(1H)I(2H)]+ leads to 1·H+ and 2·HI, which is at small collision energies accompanied by the elimination of HI leading to the desired [(1)H(2)]+ ion. The chiral effect of 1.2 is determined in favor for the formation of the homochiral complex [(1)H(2)]+.
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Weller, Michael G. « The Mystery of Homochirality on Earth ». Life 14, no 3 (6 mars 2024) : 341. http://dx.doi.org/10.3390/life14030341.

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Homochirality is an obvious feature of life on Earth. On the other hand, extraterrestrial samples contain largely racemic compounds. The same is true for any common organic synthesis. Therefore, it has been a perplexing puzzle for decades how these racemates could have formed enantiomerically enriched fractions as a basis for the origin of homochiral life forms. Numerous hypotheses have been put forward as to how preferentially homochiral molecules could have formed and accumulated on Earth. In this article, it is shown that homochirality of the abiotic organic pool at the time of formation of the first self-replicating molecules is not necessary and not even probable. It is proposed to abandon the notion of a molecular ensemble and to focus on the level of individual molecules. Although the formation of the first self-replicating, most likely homochiral molecule, is a seemingly improbable event, on a closer look, it is almost inevitable that some homochiral molecules have formed simply on a statistical basis. In this case, the non-selective leap to homochirality would be one of the first steps in chemical evolution directly out of a racemic “ocean”. Moreover, most studies focus on the chirality of the primordial monomers with respect to an asymmetric carbon atom. However, any polymer with a minimal size that allows folding to a secondary structure would spontaneously lead to asymmetric higher structures (conformations). Most of the functions of these polymers would be influenced by this inherently asymmetric folding. Furthermore, a concept of physical compartmentalization based on rock nanopores in analogy to nanocavities of digital immunoassays is introduced to suggest that complex cell walls or membranes were also not required for the first steps of chemical evolution. To summarize, simple and universal mechanisms may have led to homochiral self-replicating systems in the context of chemical evolution. A homochiral monomer pool is deemed unnecessary and probably never existed on primordial Earth.
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Qin, Ling, Qing Hu, Yang Wu, Jia-Le Cai et Yun-Yun Li. « Three novel Co(ii)/Ni(ii)-based coordination polymers as efficient heterogeneous catalysts for dye degradation ». CrystEngComm 20, no 28 (2018) : 4042–48. http://dx.doi.org/10.1039/c8ce00860d.

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Three novel Co(ii)/Ni(ii)-based coordination polymers have been synthesized and characterized. Compound 2 shows a rare 2D + 2D heterogeneous framework. Compound 3 is a chiral 0-D molecular complex driven by the solvent-assisted homochiral helix. The photocatalytic oxidation activities and mechanism have been studied.
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Kachi-Terajima, Chihiro, Megumi Ishii, Toshiaki Saito, Chikahide Kanadani, Takunori Harada et Reiko Kuroda. « Homochiral 1D Helical Chain Based on an Achiral Cu(II) Complex ». Inorganic Chemistry 51, no 14 (28 juin 2012) : 7502–7. http://dx.doi.org/10.1021/ic202708e.

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Seo, Jongcheol, Stephan Warnke, Kevin Pagel, Michael T. Bowers et Gert von Helden. « Infrared spectrum and structure of the homochiral serine octamer–dichloride complex ». Nature Chemistry 9, no 12 (10 juillet 2017) : 1263–68. http://dx.doi.org/10.1038/nchem.2821.

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Uozumi, Yasuhiro. « Asymmetric allylic substitution of cycloalkenyl esters in water with an amphiphilic resin-supported chiral palladium complex ». Pure and Applied Chemistry 79, no 9 (1 janvier 2007) : 1481–89. http://dx.doi.org/10.1351/pac200779091481.

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A novel homochiral phosphine ligand, (3R,9aS)[2-aryl-3-(2-diphenylphosphino)phenyl]tetrahydro-1H-imidazo[1,5-a]indole-1-one, was designed, prepared, and anchored onto an amphiphilic polystyrene-poly(ethylene glycol) copolymer (PS-PEG) resin. Catalytic asymmetric substitution of a racemic mixture of cycloalkenyl esters with carbon, nitrogen, and oxygen nucleophiles was achieved in water as the single reaction medium under heterogeneous conditions by using the PS-PEG resin-supported palladium-imidazoindole phosphine complex to give optically active substituted cycloalkenes with up to 99 % ee.
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16

Zee, Chih-Te, Calina Glynn, Marcus Gallagher-Jones, Jennifer Miao, Carlos G. Santiago, Duilio Cascio, Tamir Gonen, Michael R. Sawaya et Jose A. Rodriguez. « Homochiral and racemic MicroED structures of a peptide repeat from the ice-nucleation protein InaZ ». IUCrJ 6, no 2 (24 janvier 2019) : 197–205. http://dx.doi.org/10.1107/s2052252518017621.

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The ice-nucleation protein InaZ from Pseudomonas syringae contains a large number of degenerate repeats that span more than a quarter of its sequence and include the segment GSTSTA. Ab initio structures of this repeat segment, resolved to 1.1 Å by microfocus X-ray crystallography and to 0.9 Å by the cryo-EM method MicroED, were determined from both racemic and homochiral crystals. The benefits of racemic protein crystals for structure determination by MicroED were evaluated and it was confirmed that the phase restriction introduced by crystal centrosymmetry increases the number of successful trials during the ab initio phasing of the electron diffraction data. Both homochiral and racemic GSTSTA form amyloid-like protofibrils with labile, corrugated antiparallel β-sheets that mate face to back. The racemic GSTSTA protofibril represents a new class of amyloid assembly in which all-left-handed sheets mate with their all-right-handed counterparts. This determination of racemic amyloid assemblies by MicroED reveals complex amyloid architectures and illustrates the racemic advantage in macromolecular crystallography, now with submicrometre-sized crystals.
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Kachi-Terajima, Chihiro, Megumi Ishii, Toshiaki Saito, Chikahide Kanadani, Takunori Harada et Reiko Kuroda. « Correction to Homochiral 1D Helical Chain Based on an Achiral Cu(II) Complex ». Inorganic Chemistry 51, no 15 (11 juillet 2012) : 8636. http://dx.doi.org/10.1021/ic301427a.

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Lee, Seok Jong, Hye Ran Sung, Jeong-Ho Son, Rengan Ramesh et Kyo Han Ahn. « Synthesis of a homochiral carboxylate-containing tetradentate ligand and its Co(III) complex ». Inorganic Chemistry Communications 9, no 5 (mai 2006) : 518–21. http://dx.doi.org/10.1016/j.inoche.2006.02.023.

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19

Pradeep, Chullikkattil P., Panthapally S. Zacharias et Samar K. Das. « A Chiral Copper Complex Forms Supramolecular Homochiral Helices viaO-H···Cl-Cu Interactions ». European Journal of Inorganic Chemistry 2005, no 17 (septembre 2005) : 3405–8. http://dx.doi.org/10.1002/ejic.200500261.

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Li, Gao, Weibin Yu, Jia Ni, Taifeng Liu, Yan Liu, Enhong Sheng et Yong Cui. « Self-Assembly of a Homochiral Nanoscale Metallacycle from a Metallosalen Complex for Enantioselective Separation ». Angewandte Chemie International Edition 47, no 7 (1 février 2008) : 1245–49. http://dx.doi.org/10.1002/anie.200704347.

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Li, Gao, Weibin Yu, Jia Ni, Taifeng Liu, Yan Liu, Enhong Sheng et Yong Cui. « Self-Assembly of a Homochiral Nanoscale Metallacycle from a Metallosalen Complex for Enantioselective Separation ». Angewandte Chemie 120, no 7 (1 février 2008) : 1265–69. http://dx.doi.org/10.1002/ange.200704347.

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Sarkar, Shuranjan, Dohyun Moon, Seog K. Kim, Myoung Soo Lah et Hong‐In Lee. « Spontaneous Resolution Induced by a Chiral Ni(II) Complex with an Achiral Tripodal Ligand# ». Bulletin of the Korean Chemical Society 36, no 3 (18 février 2015) : 838–42. http://dx.doi.org/10.1002/bkcs.10157.

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A chiral nickel(II) complex, [Ni(II)H3L](ClO4)2 (1), with an achiral ligand H3L (=tris{2‐(4‐imidazolyl)methyliminoethyl}amine) was synthesized by in situ reaction between nickel(II) perchlorate hexahydrate and a condensation mixture of 4‐imidazolecarboxaldehyde and tris(2‐aminoethyl)amine. Single crystal X‐ray analysis revealed that the H3L ligand hexadentately binds to Ni(II) ion through three Schiff‐base imine N atoms and three imidazole N atoms with distorted octahedral geometry. Both single‐crystal X‐ray diffraction and circular dichroism investigations found that the crystal of complex 1 was an enantiopure conglomerate. The hydrogen‐bond network of NimidazoleH⋯OClO4⋯HNimidazole induced spontaneous resolution to form the conglomerate. The capped tripod‐shaped [Ni(II)H3L]2+ complex ions are hydrogen‐bonded in a tail‐to‐tail mode and array in an up‐and‐down manner repeatedly to honeycomb an extended two‐dimensional homochiral network with trigonal voids.
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Mangalath, Sreejith, Suneesh C. Karunakaran, Gary Newnam, Gary B. Schuster et Nicholas V. Hud. « Supramolecular assembly-enabled homochiral polymerization of short (dA)n oligonucleotides ». Chemical Communications 57, no 99 (2021) : 13602–5. http://dx.doi.org/10.1039/d1cc05420a.

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A goal of supramolecular chemistry is to create covalent polymers of precise composition and stereochemistry from complex mixtures by the reversible assembly of specific monomers prior to covalent bond formation.
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Meppelder, Geert-Jan M., Thomas P. Spaniol et Jun Okuda. « A binaphtolate titanium complex featuring a linear tetradentate [OSSO]-bis(phenolato) ligand : Synthesis and partial hydrolysis to a homochiral dinuclear complex ». Journal of Organometallic Chemistry 691, no 14 (juillet 2006) : 3206–11. http://dx.doi.org/10.1016/j.jorganchem.2006.02.006.

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Bagi, Péter, Réka Herbay, Gábor Györke, Péter Pongrácz, László Kollár, István Timári, László Drahos et György Keglevich. « Preparation of Palladium(II) Complexes of 1-substituted-3-phospholene Ligands and their Evaluation as Catalysts in Hydroalkoxycarbonylation ». Current Organic Chemistry 23, no 25 (14 janvier 2020) : 2873–79. http://dx.doi.org/10.2174/1385272823666191204151311.

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: A series of palladium(II) complexes incorporating 1-substituted-3-methyl-3- phospholenes as the P-ligands were prepared from phospholene oxides by deoxygenation followed by complexation with PdCl2(PhCN)2. The two 1-substituted-3-methyl-3- phospholene ligands were trans position to each other in the Pd(II)-complexes. As the ligands contain a P-stereogenic center, the Pd-complexes were obtained as a 1:1 mixture of two stereoisomers, the homochiral (R,R and S,S) and the meso (R,S) forms, when racemic starting materials were used. An optically active Pd-complex containing (R)-1-propyl- 3-phospholene ligand was also prepared. Catalytic activity of an aryl- and an alkyl-3- phospholene-palladium(II)-complex was evaluated in hydroalkoxycarbonylation of styrene. The alkyl-derivative showed higher activity and selectivity towards the formation of the esters of 3-phenylpropionic acid. However, the overall activity of these PdCl2(phospholene)2-type complexes was low.
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Liu, Cai-Ming, De-Qing Zhang, Ren-Gen Xiong, Xiang Hao et Dao-Ben Zhu. « A homochiral Zn–Dy heterometallic left-handed helical chain complex without chiral ligands : anion-induced assembly and multifunctional integration ». Chemical Communications 54, no 95 (2018) : 13379–82. http://dx.doi.org/10.1039/c8cc07468b.

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Brewer, Greg, Raymond J. Butcher et Peter Zavalij. « Use of Pyrazole Hydrogen Bonding in Tripodal Complexes to Form Self Assembled Homochiral Dimers ». Materials 13, no 7 (31 mars 2020) : 1595. http://dx.doi.org/10.3390/ma13071595.

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The 3:1 condensation of 5-methyl-1H-pyrazole-3-carboxaldehyde (MepyrzH) with tris(2-aminoethyl)amine (tren) gives the tripodal ligand tren(MePyrzH)3. Aerial oxidation of a solution of cobalt(II) with this ligand in the presence of base results in the isolation of the insoluble Co(tren)(MePyrz)3. This complex reacts with acids, HCl/NaClO4, NH4ClO4, NH4BF4, and NH4I to give the crystalline compounds Co(tren)(MePyrzH)3(ClO4)3, {[Co(tren)(MePyrzH0.5)3](ClO4)1.5}2 {[Co(tren)(MePyrzH0.5)3](BF4)1.5}2 and [Co(tren)(MePyrzH)3][Co(tren)(MePyrzH)3]I2. The latter three complexes are dimeric, held together by three Npyrazole –H…Npyrazolate hydrogen bonds. The structures and symmetries of these homochiral dimers or pseudodimers are discussed in terms of their space group. Possible applications of these complexes by incorporation into new materials are mentioned.
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Ji, Can, Shuang-Quan Zang, Jun-Yi Liu, Jia-Bin Li et Hong-Wei Hou. « Assembly of 1,2,3,4-Benzenetetracarboxylic Acid and Zinc(II) Metal Centers to a Chiral 3D Metal-organic Framework : Syntheses, Structure and Properties ». Zeitschrift für Naturforschung B 66, no 5 (1 mai 2011) : 533–37. http://dx.doi.org/10.1515/znb-2011-0514.

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A new three-dimensional metal-organic framework {[Zn(mpda)0.5(bix)]·(H2O)1.5}n (1) (H4mpda = 1,2,3,4-benzenetetracarboxylic acid, m-bix = 1,3-bis(imidazol-1-ylmethyl)-benzene) has been synthesized and characterized by single-crystal X-ray diffraction and IR spectra. In 1, homochiral helical chains are formed in the Zn-mpda layer through spontaneous resolution by mpda4−. Such layers are further connected through the second m-bix ligand to form a 3D chiral metal-organic framework. The individual (4,4)-connected net in 1 can be specified by the Schläfli symbol (66)2(64.82). Bulk material of 1 has good second-harmonic generation (SHG) activity, approximately 0.4 times that of urea. In addition, a thermogravimetric analysis was carried out, and the photoluminescent behavior of the complex was also investigated
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Seo, Chris S. G., Brian T. H. Tsui, Matthew V. Gradiski, Samantha A. M. Smith et Robert H. Morris. « Enantioselective direct, base-free hydrogenation of ketones by a manganese amido complex of a homochiral, unsymmetrical P–N–P′ ligand ». Catalysis Science & ; Technology 11, no 9 (2021) : 3153–63. http://dx.doi.org/10.1039/d1cy00446h.

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Kureshy, Rukhsana I., Surendra Singh, Noor-Ul H. Khan, Sayed H. R. Abdi, Irshad Ahmad, Achyut Bhatt et Raksh V. Jasra. « Improved catalytic activity of homochiral dimeric cobalt-salen complex in hydrolytic kinetic resolution of terminal racemic epoxides ». Chirality 17, no 9 (2005) : 590–94. http://dx.doi.org/10.1002/chir.20196.

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Matveevskaya, Vladislava, Dmitry Pavlov et Andrei Potapov. « Iridium(III) and Rhodium(III) Half-Sandwich Coordination Compounds with 11H-Indeno[1,2-b]quinoxalin-11-one Oxime : A Case of Spontaneous Resolution of Rh(III) Complex ». Inorganics 10, no 11 (25 octobre 2022) : 179. http://dx.doi.org/10.3390/inorganics10110179.

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Two half-sandwich iridium(III) and rhodium(III) complexes with 11H-indeno[1,2-b]quinoxalin-11-one oxime (IQ-1) ligand were prepared by the reaction of the proligand with [M(Cp*)Cl2]2 (M = Ir, Rh) dimers. The reaction between IQ-1 and [Ir(Cp*)Cl2]2 in methanol gave the complex [Ir(Cp*)(IQ-1)Cl] (1), which crystallized in a centrosymmetric space group as a true racemate. Whereas complex [Rh(Cp*)(IQ-1)Cl] (2) in the form of a racemic conglomerate was obtained by the reaction of [Rh(Cp*)Cl2]2 and IQ-1 in methanol. The crystal structures of complexes 1 and 2 (R and S enantiomers) were determined by X-ray diffraction analysis, and the structural features were compared in order to understand the structural factors leading to the spontaneous enantiomer resolution of the rhodium(III) complex. In the crystal packing of 1, intermolecular C–H···C contacts between a pair of enantiomers link the molecules into centrosymmetric dimers and lead to the formation of heterochiral crystals of 1. In contrast, the intramolecular contacts CH···Cl and CH···C in complex 2 bind all three ligands around the chiral Rh(III) metal center. In addition, a combination of intermolecular CH···O and CH···C contacts leads to the formation of a homochiral supramolecular structure. These interactions altogether reinforce the spontaneous resolution in complex 2.
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Ramiro, José Luis, Sonia Martínez-Caballero, Ana G. Neo, Jesús Díaz et Carlos F. Marcos. « The Castagnoli–Cushman Reaction ». Molecules 28, no 6 (15 mars 2023) : 2654. http://dx.doi.org/10.3390/molecules28062654.

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Since the first reports of the reaction of imines and cyclic anhydrides by Castagnoli and Cushman, this procedure has been applied to the synthesis of a variety of lactams, some of them with important synthetic or biological interest. The scope of the reaction has been extended to the use of various Schiff bases and anhydrides as well as to different types of precursors for these reagents. In recent years, important advances have been made in understanding the mechanism of the reaction, which has historically been quite controversial. This has helped to develop reaction conditions that lead to pure diastereomers and even homochiral products. In addition, these mechanistic studies have also led to the development of new multicomponent versions of the Castagnoli–Cushman reaction that allow products with more diverse and complex molecular structures to be easily obtained.
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Verdugo-Torres, Brayan David, Jairo Antonio Cubillos-Lobo et Hugo Alfonso Rojas-Sarmiento. « Enantioselective epoxidation of styrene using in-situ generated dimethyldioxirane and dimeric homochiral Mn(III)-Schiff base complex catalyst ». Revista Facultad de Ingeniería Universidad de Antioquia, no 89 (2018) : 73–80. http://dx.doi.org/10.17533/udea.redin.n89a10.

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Kureshy, Rukhsana Ilyas, Noor-ul Hasan Khan, Sayed Hasan Razi Abdi, Irshad Ahmed, Surendra Singh et Raksh Vir Jasra. « Enantioselective epoxidation of non-functionalised alkenes catalysed by dimeric homochiral Mn(III) Salen complex using oxone as oxidant ». Journal of Molecular Catalysis A : Chemical 203, no 1-2 (septembre 2003) : 69–73. http://dx.doi.org/10.1016/s1381-1169(03)00258-9.

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García-Deibe, Ana M., Matilde Fondo, Julio Corredoira-Vázquez, M. Salah El Fallah et Jesús Sanmartín-Matalobos. « Hierarchical Assembly of Antiparallel Homochiral Sheets Formed by Hydrogen-Bonded Helixes of a Trapped-Valence CoII/CoIII Complex ». Crystal Growth & ; Design 17, no 2 (20 janvier 2017) : 467–73. http://dx.doi.org/10.1021/acs.cgd.6b01269.

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Řezanka, Tomáš, Andrea Palyzová, Milada Vítová, Tomáš Brányik, Markéta Kulišová et Jarošová Kolouchová Irena. « Structural Characterization of Mono- and Dimethylphosphatidylethanolamines from Various Organisms Using a Complex Analytical Strategy including Chiral Chromatography ». Symmetry 14, no 3 (19 mars 2022) : 616. http://dx.doi.org/10.3390/sym14030616.

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Two minor phospholipids, i.e., mono- and/or dimethylphosphatidylethanolamines, are widespread in many organisms, from bacteria to higher plants and animals. A molecular mixture of methyl-PE and dimethyl-PE was obtained from total lipids by liquid chromatography and further identified by mass spectrometry. Total methyl-PE and dimethyl-PE were cleaved by phospholipase C, and the resulting diacylglycerols, in the form of acetyl derivatives, were separated into alkyl-acyl, alkenyl-acyl, and diacylglycerols. Reversed-phase LC/MS allowed dozens of molecular species to be identified and further analyzed. This was performed on a chiral column, and identification by tandem positive ESI revealed that diacyl derivatives from all four bacteria were mixtures of both R and S enantiomers. The same applied to alkenyl-acyl derivatives of anaerobic bacteria. Analysis thus confirmed that some bacteria biosynthesize phospholipids having both sn-glycerol-3-phosphate and sn-glycerol-1-phosphate as precursors. These findings were further supported by data already published in GenBank. The use of chiral chromatography made it possible to prove that both enantiomers of glycerol phosphate of some molecular species of mono- and dimethylphosphatidylethanolamines are present. The result of the analysis can be interpreted that the cultured bacteria do not have homochiral membranes but, on the contrary, have an asymmetric, i.e., heterochiral membranes.
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37

Sellmann, Dieter, Frank W. Heinemann et Torsten Gottschalk-Gaudig. « Structure of [μ-S2{Ru(PCy3)('S4')}2] · 2.5 THF ·0.5 Et2O Containing Homochiral Metal Complex Fragments ['S4'2- = 1,2-Bis(mercaptophenylthio)-ethane (2-)] ». Zeitschrift für Naturforschung B 54, no 9 (1 septembre 1999) : 1122–24. http://dx.doi.org/10.1515/znb-1999-0905.

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A crystal of the title compound [μ-S2{Ru(PCy3)(′S4′)}2] · 2.5 THF · 0.5 Et2O (1 · 2.5 THF · 0.5 Et2O), grown from a THF/Et2O solution, was investigated by single-crystal X-ray analysis. 1 · 2.5 THF · 0.5 Et2O crystallizes in the triclinic space group P1̄ with a = 14.209(4), b = 15.390(4), c = 19.526(6) Å, α = 111.29(2), ß = 100.43(2), γ = 95.65(2)°, and Z = 2. The crystal structure was solved by direct methods (wR2= 0.1520 for 12565 reflections; R1 = 0.0507 for 9205 observed reflections). The molecular structure of 1 · 2.5 THF · 0.5 Et2O is characterized by a trans η1 -η1-S2 bridge connecting two homochiral [Ru(PCy3)(′S4′)] fragments. The S-S bond length of 1.982(2) Å and a mean Ru-S(bridge) distance of 2.234(2) Å indicate partial double bond character of these bonds. The RuSSRu unit in 1 · 2.5 THF · 0.5 Et2O is a chromophore as indicated by its UV spectrum and can be described by a delocalized 4c-6e 7π system.
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38

Wang, Qiang, Shari Venneri, Niloofar Zarrabi, Hongfeng Wang, Cédric Desplanches, Jean-François Létard, Takele Seda et Melanie Pilkington. « Stereochemistry for engineering spin crossover : structures and magnetic properties of a homochiral vs. racemic [Fe(N3O2)(CN)2] complex ». Dalton Transactions 44, no 15 (2015) : 6711–14. http://dx.doi.org/10.1039/c5dt00357a.

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39

Boiocchi, Massimo, et Luigi Fabbrizzi. « Double-stranded dimetallic helicates : assembling–disassembling driven by the CuI/CuII redox change and the principle of homochiral recognition ». Chem. Soc. Rev. 43, no 6 (2014) : 1835–47. http://dx.doi.org/10.1039/c3cs60428d.

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Upon reduction of a mononuclear complex of CuII with a tetradentate ligand (a racemic mixture of the S,S and R,R enantiomers) two dicopper(i) double stranded helicates form, each one containing strands of the same chirality.
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Kazemi, Zahra, Hadi Amiri Rudbari, Mehdi Sahihi, Valiollah Mirkhani, Majid Moghadam, Shahram Tangestaninejad, Iraj Mohammadpoor-Baltork et Abolghasem Abbasi Kajani. « New homochiral and heterochiral Mo(VI) complex from racemic ligand : Synthesis, X-ray structure, diastereomers separation and biological activities ». Polyhedron 170 (septembre 2019) : 70–85. http://dx.doi.org/10.1016/j.poly.2019.05.021.

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Ajayi, Tomilola J., Amanda L. Kwan, Alan J. Lough et Robert H. Morris. « A homochiral Nickel(II) complex [Ni(P'N)2]Cl2 : Synthesis, characterization, crystal structure, luminescence, DFT and Hirshfeld surface studies ». Journal of Molecular Structure 1322 (février 2025) : 140292. http://dx.doi.org/10.1016/j.molstruc.2024.140292.

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Fox, Allison C., Jason D. Boettger, Eve L. Berger et Aaron S. Burton. « The Role of the CuCl Active Complex in the Stereoselectivity of the Salt-Induced Peptide Formation Reaction : Insights from Density Functional Theory Calculations ». Life 13, no 9 (23 août 2023) : 1796. http://dx.doi.org/10.3390/life13091796.

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The salt-induced peptide formation (SIPF) reaction is a prebiotically plausible mechanism for the spontaneous polymerization of amino acids into peptides on early Earth. Experimental investigations of the SIPF reaction have found that in certain conditions, the l enantiomer is more reactive than the d enantiomer, indicating its potential role in the rise of biohomochirality. Previous work hypothesized that the distortion of the CuCl active complex toward a tetrahedral-like structure increases the central chirality on the Cu ion, which amplifies the inherent parity-violating energy differences between l- and d-amino acid enantiomers, leading to stereoselectivity. Computational evaluations of this theory have been limited to the protonated–neutral l + l forms of the CuCl active complex. Here, density functional theory methods were used to compare the energies and geometries of the homochiral (l + l and d + d) and heterochiral (l + d) CuCl–amino acid complexes for both the positive–neutral and neutral–neutral forms for alanine, valine, and proline. Significant energy differences were not observed between different chiral active complexes (i.e., d + d, l + l vs. l + d), and the distortions of active complexes between stereoselective systems and non-selective systems were not consistent, indicating that the geometry of the active complex is not the primary driver of the observed stereoselectivity of the SIPF reaction.
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43

Sellmann, Dieter, Helge Friedrich et Falk Knoch. « Übergangsmetallkomplexe mit Schwefelliganden, XCIX. Bildung und Struktur von [Fe(′S4′)]4. Eine bemerkenswerte Tetramerisierung homochiraler[Fe(′S4′)]-Komplexfragmente (′S4′2- = 1,2-Bis(2-mercaptophenylthio)ethan(2-)) / Transition Metal Complexes with Sulfur Ligands, XCIX. Formation and Structure of [Fe(′S4′)]4. A Remarkable Tetramerization of Homochiral [Fe(′S4′)] Complex Fragments (′S4′2-= 1,2-Bis(2-mercaptophenylthio)ethane(2–)) ». Zeitschrift für Naturforschung B 48, no 11 (1 novembre 1993) : 1675–80. http://dx.doi.org/10.1515/znb-1993-1128.

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In MeOH/THF solution, Fe(II) ions and the tetradentate thioether-thiolate ′S4′2-([1,2-Bis(2-mercaptophenylthio)ethane(2-)]) slowly form the tetrameric [Fe(′S4′)]4 1. The crystal structure of 1 · THF • 2 MeOH was determined by X-ray structure analysis. Chiral 1 crystallizes as a pair of enantiomers each of which consist of four homochiral [Fe(′S4′)] fragments bridged via μ2- and µ3-S(thiolato) donors; stereochemical aspects of the enantiospecific tetramerization of [Fe(′S4′)] fragments are discussed. In strong polar solvents such as dimethylformamide, dissociation of [Fe(′S4′)]4 into [Fe(′S4′)]2 fragments is indicated by the formation of [Fe(CO)(′S4′)]2 upon reaction with CO.
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44

Wölper, Christoph, Sara Durán Ibáńez et Peter G. Jones. « Amine-rich Silver Complexes of rac-trans-1,2-Diaminocyclohexane ». Zeitschrift für Naturforschung B 65, no 10 (1 octobre 2010) : 1249–57. http://dx.doi.org/10.1515/znb-2010-1012.

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The use of the diamine rac-trans-1,2-diaminocyclohexane (LL) as a major component of the solvent system allows the isolation of crystalline silver complexes with higher ratios of LL to silver (up to 4 : 1, compared to the previously obtained 1 : 1 in ethanolic solution). The complexes obtained and crystallographically characterized were (LL)2AgNO3 (1), (LL)3Ag(OAc)(H2O)2 (2) and (LL)4AgBr(H2O)3 (3). Additionally, the silver-free compounds (LL)・(H2O) (4) and (LL)3・HCl (5) were obtained as by-products. Complex 1 is a chain polymer with one bridging and one terminal LL ligand; the chains are homochiral. Complex 2 contains isolated [(LL)3Ag]+ cations with one chelating and two monodentate ligands. Complex 3 contains dimeric [(LL)2AgBr]2 units; the additional LL molecules are not coordinated to the metal. Compound 5 consists of one diamine with imposed twofold symmetry, one half-protonated diamine in which the acidic hydrogen site is half-occupied (it is involved in a disordered hydrogen bond N-H・ ・ ・N across a twofold axis) and a chloride anion on a twofold axis. In all five structures, the components pack so as to form clearly defined hydrophilic and hydrophobic areas. In the former, classical hydrogen bonds are formed. Except for a few borderline cases of three-center bonds, these are all two-center systems. The appreciable number of these (e. g. 20 for compound 3) renders the layer structures quite complex, but in most cases they can be analyzed in terms of smaller units.
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Morvan, Marine, et Ivan Mikšík. « Recent Advances in Chiral Analysis of Proteins and Peptides ». Separations 8, no 8 (29 juillet 2021) : 112. http://dx.doi.org/10.3390/separations8080112.

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Like many biological compounds, proteins are found primarily in their homochiral form. However, homochirality is not guaranteed throughout life. Determining their chiral proteinogenic sequence is a complex analytical challenge. This is because certain d-amino acids contained in proteins play a role in human health and disease. This is the case, for example, with d-Asp in elastin, β-amyloid and α-crystallin which, respectively, have an action on arteriosclerosis, Alzheimer’s disease and cataracts. Sequence-dependent and sequence-independent are the two strategies for detecting the presence and position of d-amino acids in proteins. These methods rely on enzymatic digestion by a site-specific enzyme and acid hydrolysis in a deuterium or tritium environment to limit the natural racemization of amino acids. In this review, chromatographic and electrophoretic techniques, such as LC, SFC, GC and CE, will be recently developed (2018–2020) for the enantioseparation of amino acids and peptides. For future work, the discovery and development of new chiral stationary phases and derivatization reagents could increase the resolution of chiral separations.
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Cambie, RC, KC Higgs, JJ Rustenhoven et PS Rutledge. « Experiments Directed Towards the Synthesis of Anthracyclinones. XXIX. Fluoro-Substituted Tetracycles ». Australian Journal of Chemistry 49, no 7 (1996) : 751. http://dx.doi.org/10.1071/ch9960751.

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Diastereoselective formation of 9-fluoro-9-methylanthracyclinones has been achieved by treating ortho-methallyl-substituted anthraquinonyl homochiral dioxans with boron trifluoride etherate . The demethoxy anthraquinonyl dioxan (16) underwent slow reaction to give exclusively the (7S,9R) fluoro tetracycle (21) in 58% yield. The dimethoxy anthraquinonyl dioxan (15) was less reactive, allowing other reactions to compete, but boron trifluoride -acetic acid complex effected rapid cyclization of (15) with high diastereoselectivity. Short reaction times with this reagent circumvented the formation of the alkenes (25) and the naphthacenedione (9). Boron trifluoride-nitromethane gave the (7S,9R) fluoro tetracycle (19) in 36% yield. Although the yields of the fluoro tetracycles were modest, they compare favourably with a 4% yield reported for the fluorination of daunomycinone. The 6-demethoxy tetracycle (21) has been shown to exist in the expected half-chair conformation, with the bulky C7 side chain in a pseudo-equatorial position. In contrast, the 6,11-dimethoxy fluoro tetracycle (19) exists in a significantly perturbed half-chair conformation with a pseudo-axial side chain.
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Shi, Wei, Jian-Jun Liu, Xiang-Ping Ou et Chang-Cang Huang. « A three-dimensional cadmium(II) coordination polymer with unequal homochiral double-stranded concentric helical chains ». Acta Crystallographica Section C Structural Chemistry 71, no 4 (14 mars 2015) : 289–93. http://dx.doi.org/10.1107/s2053229615004258.

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A homochiral helical three-dimensional coordination polymer, poly[[(μ2-acetato-κ3O,O′:O)(hydroxido-κO)(μ4-5-nicotinamido-1H-1,2,3,4-tetrazol-1-ido-κ5N1,O:N2:N4:N5)(μ3-5-nicotinamido-1H-1,2,3,4-tetrazol-1-ido-κ4N1,O:N2:N4:N5)dicadmium(II)] 0.75-hydrate], {[Cd2(C7H5N6O)2(CH3COO)(OH)]·0.75H2O}n, was synthesized by the reaction of cadmium acetate,N-(1H-tetrazol-5-yl)isonicotinamide (H-NTIA), ethanol and H2O under hydrothermal conditions. The asymmetric unit contains two crystallographically independent CdIIcations, two deprotonated 5-nicotinamido-1H-1,2,3,4-tetrazol-1-ide (NTIA−) ligands, one acetate anion, one hydroxide anion and three independent partially occupied water sites. The two CdIIcations, with six-coordinated octahedral and seven-coordinated pentagonal bipyramidal geometries are located on general sites. The tetrazole group of one symmetry-independent NTIA−ligand links one of the independent CdIIcations into 61helical chains, while the other NTIA−ligand links the other independent CdIIcations into similar but unequal 61helical chains. These chains, with a pitch of 24.937 (5) Å, intertwine into a double-stranded helix. Each of the double-stranded 61helices is further connected to six adjacent helical chains through an acetate μ2-O atom and the tetrazole group of the NTIA−ligand into a three-dimensional framework. The helical channel is occupied by the isonicotinamide groups of NTIA−ligands and two helices are connected to each other through the pyridine N and carbonyl O atoms of isonicotinamide groups. In addition, N—H...O and O—H...N hydrogen bonds exist in the complex.
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Djukic, Jean-Pierre, Jean-Baptiste Sortais, Laurent Barloy, Nicolas Pannetier, Claude Sirlin et Michel Pfeffer. « Synthesis, Characterization, and Fluxional Behavior of a 34 Electron Homochiral Dimetallic Complex with an Unsupported Hydride Bridge between Two Ru Atoms ». Organometallics 31, no 7 (16 février 2012) : 2821–28. http://dx.doi.org/10.1021/om201093y.

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49

Kasák, Peter, et Martin Putala. « Stereoconservative Cyanation of [1,1'-Binaphthalene]-2,2'-dielectrophiles. An Alternative Approach to Homochiral C2-Symmetric [1,1'-Binaphthalene]-2,2'-dicarbonitrile and Its Transformations ». Collection of Czechoslovak Chemical Communications 65, no 5 (2000) : 729–40. http://dx.doi.org/10.1135/cccc20000729.

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The performed study on the cyanation of [1,1'-binaphthalene]-2,2'-diiodide and [1,1'-binaph- thalene]-2,2'-diyl ditriflate showed reactions with zinc cyanide catalyzed by palladium phosphane complex in DMF to be the most effective procedures with almost complete conservation of stereogenic information - affording corresponding highly enantiomerically enriched dinitrile (from diiodide: 94% yield, 92% ee). Dinitrile was successfully transformed into [1,1'-binaphthalene]-2,2'-dicarboxylic acid and -2,2'-dicarbaldehyde in high yields (84-87%).
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50

Lee, Carina, Jessica M. Weber, Laura E. Rodriguez, Rachel Y. Sheppard, Laura M. Barge, Eve L. Berger et Aaron S. Burton. « Chirality in Organic and Mineral Systems : A Review of Reactivity and Alteration Processes Relevant to Prebiotic Chemistry and Life Detection Missions ». Symmetry 14, no 3 (24 février 2022) : 460. http://dx.doi.org/10.3390/sym14030460.

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Chirality is a central feature in the evolution of biological systems, but the reason for biology’s strong preference for specific chiralities of amino acids, sugars, and other molecules remains a controversial and unanswered question in origins of life research. Biological polymers tend toward homochiral systems, which favor the incorporation of a single enantiomer (molecules with a specific chiral configuration) over the other. There have been numerous investigations into the processes that preferentially enrich one enantiomer to understand the evolution of an early, racemic, prebiotic organic world. Chirality can also be a property of minerals; their interaction with chiral organics is important for assessing how post-depositional alteration processes could affect the stereochemical configuration of simple and complex organic molecules. In this paper, we review the properties of organic compounds and minerals as well as the physical, chemical, and geological processes that affect organic and mineral chirality during the preservation and detection of organic compounds. We provide perspectives and discussions on the reactions and analytical techniques that can be performed in the laboratory, and comment on the state of knowledge of flight-capable technologies in current and future planetary missions, with a focus on organics analysis and life detection.
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