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1.
5,20‐Bis(ethoxycarbonyl)‐[28]hexaphyrin was synthesized by acid catalyzed cross‐condensation of meso‐diaryl‐substituted tripyrrane and ethyl 2‐oxoacetate followed by subsequent oxidation. This hexaphyrin was found to be a stable 28π‐antiaromatic compound with a dumbbell‐like conformation. Upon oxidization with PbO2, this [28]hexaphyrin was converted into an aromatic [26]hexaphyrin with a rectangular shape bearing two ester groups at the edge side. The [28]hexaphyrin can incorporate two NiII or CuII metals by using the ester carbonyl groups and three pyrrolic nitrogen atoms to give bis‐NiII and bis‐CuII complexes with essentially the same dumbbell‐like structure. The antiaromatic properties of the [28]hexaphyrin and its metal complexes have been well characterized. 相似文献
2.
Redox‐Switchable 20π‐, 19π‐, and 18π‐Electron 5,10,15,20‐Tetraaryl‐5,15‐diazaporphyrinoid Nickel(II) Complexes 下载免费PDF全文
Takaharu Satoh Prof. Dr. Mao Minoura Prof. Dr. Haruyuki Nakano Prof. Dr. Ko Furukawa Prof. Dr. Yoshihiro Matano 《Angewandte Chemie (International ed. in English)》2016,55(6):2235-2238
The first examples of air‐stable 20π‐electron 5,10,15,20‐tetraaryl‐5,15‐diaza‐5,15‐dihydroporphyrins, their 18π‐electron dications, and the 19π‐electron radical cation were prepared through metal‐templated annulation of nickel(II) bis(5‐arylamino‐3‐chloro‐8‐mesityldipyrrin) complexes followed by oxidation. The neutral 20π‐electron derivatives are antiaromatic and the cationic 18π‐electron derivatives are aromatic in terms of the magnetic criterion of aromaticity. The meso N atoms in these diazaporphyrinoids give rise to characteristic redox and optical properties for the compounds that are not typical of isoelectronic 5,10,15,20‐tetraarylporphyrins. 相似文献
3.
(Dibenzoylmethanato)boron Difluoride Derivatives Containing Triphenylamine Moieties: A New Type of Electron‐Donor/π‐Acceptor System for Dye‐Sensitized Solar Cells 下载免费PDF全文
Yosuke Mizuno Yilihamu Yisilamu Tomoya Yamaguchi Dr. Masaaki Tomura Dr. Takashi Funaki Dr. Hideki Sugihara Prof. Dr. Katsuhiko Ono 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13286-13295
(Dibenzoylmethanato)boron difluoride derivatives containing triphenylamine moieties were synthesized as a new type of electron‐donor/π‐acceptor system. These new compounds exhibited long‐wavelength absorptions in the UV/Vis spectra, and reversible oxidation and reduction waves in cyclic voltammetry experiments. Their amphoteric redox properties are based on their resonance hybrid forms, in which a positive charge is delocalized on the triphenylamine moieties and a negative charge is localized on the boron atoms. Molecular orbital (MO) calculations indicate that their HOMO and LUMO energies vary with the number of phenylene rings connected to the difluoroboron‐chelating ring. This is useful for optimizing the HOMO and LUMO levels to an iodine redox (I?/I3?) potential and a titanium dioxide conduction band, respectively. Dye‐sensitized solar cells fabricated by using these compounds as dye sensitizers exhibited solar‐to‐electric power conversion efficiencies of 2.7–4.4 % under AM 1.5 solar light. 相似文献
4.
Jayaprakash Ajay Sriram Shirisha Dr. Masatoshi Ishida Kosuke Ito Dr. Shigeki Mori Prof. Dr. Hiroyuki Furuta Dr. Sabapathi Gokulnath 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(11):2859-2867
The Lewis acid catalyzed self-condensation of hybrid diheterole (furan-pyrrole and thiophene-pyrrole) precursors has afforded novel Hückel antiaromatic 24π hexaphyrin(1.0.1.0.1.0) and 32π octaphyrin(1.0.1.0.1.0.1.0) structures without β-annulated bridges. Single-crystal X-ray diffraction analysis of the hybrid porphyrinoids ( S3N3-ox and O4N4-ox ) revealed a nearly planar conformation and the 1H NMR spectra suggest the presence of paratropic ring currents. These antiaromatic macrocycles show characteristic optical features and underwent reversible two-electron reduction to Hückel aromatic 26π- and 34π-electron species, respectively, as is evident from the results of spectroscopic and theoretical studies (nucleus-independent chemical shift (NICS) and anisotropy of the current-induced density (ACID) calculations). The incorporation of hybrid diheteroles alternately into expanded porphyrin skeletons provides a novel approach to the fine-tuning of the electronic structures of planar antiaromatic macrocycles. 相似文献
5.
Rational Synthesis of Antiaromatic 5,15‐Dioxaporphyrin and Oxidation into β,β‐Linked Dimers 下载免费PDF全文
Akihide Nishiyama Masaya Fukuda Dr. Shigeki Mori Prof. Dr. Ko Furukawa Dr. Heike Fliegl Prof. Dr. Hiroyuki Furuta Prof. Dr. Soji Shimizu 《Angewandte Chemie (International ed. in English)》2018,57(31):9728-9733
5,15‐Dioxaporphyrin was synthesized for the first time by a nucleophilic aromatic substitution reaction of a nickel bis(α,α′‐dibromodipyrrin) complex with benzaldoxime, followed by an intramolecular annulation of the α‐hydroxy‐substituted intermediate. This unprecedented molecule is a 20π‐electron antiaromatic system, in terms of Hückel's rule of aromaticity, because lone pair electrons of oxygen atoms are incorporated into the 18π‐electron conjugated system of the porphyrin. A theoretical analysis based on the gauge‐including magnetically induced current method confirmed its antiaromaticity and a dominant inner ring pathway for the ring current. The unique reactivity of 5,15‐dioxaporphyrin forming a β,β‐linked dimer upon oxidation was also revealed. 相似文献
6.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(44):14017-14020
Benzodisilacyclobutadienes 2 a – c were isolated as blue to green crystalline solids from the reaction of stable disilyne 1 and 1,2‐dibromobenzenes in the presence of potassium graphite. In the solid state, substantial bond alternation was observed within the benzene rings of 2 a – c . In hexane, 2 a – c showed remarkable bathochromic shifts of the π→π* (HOMO→LUMO) absorption bands at 625–670 nm. NMR spectra and theoretical calculations indicated that the diamagnetic ring currents of the benzene rings of 2 a – c are considerably reduced by contributions from the antiaromatic 1,2‐disilacyclobutadienes. In their entirety, the obtained results indicate that 2 a – c represent 8π‐electron systems that contain an antiaromatic 1,2‐disilacyclobutadiene. 相似文献
7.
Simultaneous Induction of Axial and Planar Chirality in Arene–Chromium Complexes by Molybdenum‐Catalyzed Enantioselective Ring‐Closing Metathesis 下载免费PDF全文
Prof.Dr. Ken Kamikawa Dr. Sachie Arae Dr. Wei‐Yi Wu Chihiro Nakamura Prof.Dr. Tamotsu Takahashi Prof.Dr. Masamichi Ogasawara 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4954-4957
The molybdenum‐catalyzed asymmetric ring‐closing metathesis of the various Cs‐symmetric (π‐arene)chromium substrates provides the corresponding bridged planar‐chiral (π‐arene)chromium complexes in excellent yields with up to >99 % ee. With a bulky and unsymmetrical substituent, such as N‐indolyl or 1‐naphthyl, at the 2‐positions of the η6‐1,3‐diisopropenylbenzene ligands, both biaryl‐based axial chirality and π‐arene‐based planar chirality are simultaneously induced in the products. The axial chirality is retained even after the removal of the dicarbonylchromium fragment, and the chiral biaryl/heterobiaryl compounds are obtained with complete retention of the enantiopurity. 相似文献
8.
David K. Geiger H. Cristina Geiger Jared M. Deck 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(12):1125-1132
The synthesis and structural characterization of 2‐(furan‐2‐yl)‐1‐(furan‐2‐ylmethyl)‐1H‐benzimidazole [C16H12N2O2, (I)], 2‐(furan‐2‐yl)‐1‐(furan‐2‐ylmethyl)‐1H‐benzimidazol‐3‐ium chloride monohydrate [C16H13N2O2+·Cl−·H2O, (II)] and the hydrobromide salt 5,6‐dimethyl‐2‐(furan‐2‐yl)‐1‐(furan‐2‐ylmethyl)‐1H‐benzimidazol‐3‐ium bromide [C18H17N2O2+·Br−, (III)] are described. Benzimidazole (I) displays two sets of aromatic interactions, each of which involves pairs of molecules in a head‐to‐tail arrangement. The first, denoted set (Ia), exhibits both intermolecular C—H...π interactions between the 2‐(furan‐2‐yl) (abbreviated as Fn) and 1‐(furan‐2‐ylmethyl) (abbreviated as MeFn) substituents, and π–π interactions involving the Fn substituents between inversion‐center‐related molecules. The second, denoted set (Ib), involves π–π interactions involving both the benzene ring (Bz) and the imidazole ring (Im) of benzimidazole. Hydrated salt (II) exhibits N—H...OH2...Cl hydrogen bonding that results in chains of molecules parallel to the a axis. There is also a head‐to‐head aromatic stacking of the protonated benzimidazole cations in which the Bz and Im rings of one molecule interact with the Im and Fn rings of adjacent molecules in the chain. Salt (III) displays N—H...Br hydrogen bonding and π–π interactions involving inversion‐center‐related benzimidazole rings in a head‐to‐tail arrangement. In all of the π–π interactions observed, the interacting moieties are shifted with respect to each other along the major molecular axis. Basis set superposition energy‐corrected (counterpoise method) interaction energies were calculated for each interaction [DFT, M06‐2X/6‐31+G(d)] employing atomic coordinates obtained in the crystallographic analyses for heavy atoms and optimized H‐atom coordinates. The calculated interaction energies are −43.0, −39.8, −48.5, and −55.0 kJ mol−1 for (Ia), (Ib), (II), and (III), respectively. For (Ia), the analysis was used to partition the interaction energies into the C—H...π and π–π components, which are 9.4 and 24.1 kJ mol−1, respectively. Energy‐minimized structures were used to determine the optimal interplanar spacing, the slip distance along the major molecular axis, and the slip distance along the minor molecular axis for 2‐(furan‐2‐yl)‐1H‐benzimidazole. 相似文献
9.
K. Harikrishna Reddy Dr. Dandamudi Usharani Prof. John F. Nixon Prof. Eluvathingal D. Jemmis 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(33):9142-9152
The potential energy surfaces of both neutral and dianionic SnC2P2R2 (R=H, tBu) ring systems have been explored at the B3PW91/LANL2DZ (Sn) and 6‐311+G* (other atoms) level. In the neutral isomers the global minimum is a nido structure in which a 1,2‐diphosphocyclobutadiene ring (1,2‐DPCB) is capped by the Sn. Interestingly, the structure established by X‐ray diffraction analysis, for R=tBu, is a 1,3‐DPCB ring capped by Sn and it is 2.4 kcal mol?1 higher in energy than the 1,2‐DPCB ring isomer. This is possibly related to the kinetic stability of the 1,3‐DPCB ring, which might originate from the synthetic precursor ZrCp2tBu2C2P2. In the case of the dianionic isomers we observe only a 6π‐electron aromatic structure as the global minimum, similarly to the cases of our previously reported results with other types of heterodiphospholes. 1 , 4 , 19 The existence of large numbers of cluster‐type isomers in neutral and 6π‐planar structures in the dianions SnC2P2R22? (R=H, tBu) is due to 3D aromaticity in neutral clusters and to 2D π aromaticity of the dianionic rings. Relative energies of positional isomers mainly depend on: 1) the valency and coordination number of the Sn centre, 2) individual bond strengths, and 3) the steric effect of tBu groups. A comparison of neutral stannadiphospholes with other structurally related C5H5+ analogues indicates that Sn might be a better isolobal analogue to P+ than to BH or CH+. The variation in global minima in these C5H5+ analogues is due to characteristic features such as 1) the different valencies of C, B, P and Sn, 2) the electron deficiency of B, 3) weaker pπ–pπ bonding by P and Sn atoms, and 4) the tendency of electropositive elements to donate electrons to nido clusters. Unlike the C5H5+ systems, all C5H5? analogues have 6π‐planar aromatic structures as global minima. The differences in the relative ordering of the positional isomers and ligating properties are significant and depend on 1) the nature of the π orbitals involved, and 2) effective overlap of orbitals. 相似文献
10.
Joel Donkeng Dazie Alan Lika Jií Ludvík Jan Fbry Michal Duek 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(7):518-524
Orthophthalaldehyde (o‐phthalaldehyde, OPA) is an aromatic dialdehyde bearing two electron‐withdrawing carbonyl groups. The reactions of OPA with primary amines are broadly applied for the synthesis of important heterocyclic compounds with biological relevance. A number of such reactions have been investigated recently and several structures of condensation products have been reported, however, the complex reaction mechanism is still not fully understood and comprises concurrent as well as consecutive reactions. The reaction products depend on the primary amine which reacts with OPA, the reaction environment (solvent) and the proportion of the reactants. The title molecule, C11H13NO, the product of the reaction of OPA with isopropylamine, contains a five‐membered pyrrole C4N ring with a carbonyl substituent, which forms part of the isoindolinone unit. Though this pyrrole ring contains one C atom in the sp3‐hybridized state, it is fairly planar. The title molecule has been compared with similar structures retrieved from the Cambridge Structural Database in order to study this phenomenon. The planarity of this fragment has been explained by the presence of partially delocalized C—C, C—N and C—O bonds, and by an inner angle in the planar pentagonal ring (∼108°), which is close to the ideal tetrahedral value for the sp3‐hybridized state of the constituent C atom. Due to this propitious angle, this C atom can be present in states intermediate between sp3‐ and sp2‐hybridized in different structures, while still maintaining the planarity of the ring. There are only weak intermolecular C—H…O hydrogen bonds and C—H…π‐electron ring interactions in the structure. In particular, it is the pyrrole ring which is involved in these interactions. 相似文献
11.
Jorge Trilleras Jairo Quiroga Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(1):o11-o14
2‐Amino‐4‐chloro‐5‐formyl‐6‐[methyl(2‐methylphenyl)amino]pyrimidine, C13H13ClN4O, (I), and 2‐amino‐4‐chloro‐5‐formyl‐6‐[(2‐methoxyphenyl)methylamino]pyrimidine, C13H13ClN4O2, (II), are isostructural and essentially isomorphous. Although the pyrimidine rings in each compound are planar, the ring‐substituent atoms show significant displacements from this plane, and the bond distances provide evidence for polarization of the electronic structures. In each compound, a combination of N—H...N and N—H...O hydrogen bonds links the molecules into sheets built from centrosymmetric R22(8) and R66(32) rings. The significance of this study lies in its observation of the isostructural nature of (I) and (II), and in the comparison of their crystal and molecular structures with those of analogous compounds. 相似文献
12.
Xin‐Qiang Wang Wen‐Tao Yu Dong Xu Yan‐Ling Wang Ting‐Bin Li Wen‐Feng Guo 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(10):o583-o585
The title compound, C13H6O4S5, possesses crystallographically imposed mirror symmetry, with the atoms of the C=S group lying on the mirror plane. It is an example of the general formula [RCO]2(dmit), where R is a furan ring and dmit is 2‐thioxo‐1,3‐dithiole‐4,5‐dithiolate. The components exhibit some polarization of their molecular–electronic structure. The dmit and furan moieties exhibit a high degree of conjugation, as the introduction of C=O connecting the conjugated furan (donor) and dmit (acceptor) rings forms a good conjugated system with high delocalization. A polar three‐dimensional framework is built from a combination of intermolecular contacts, namely S⋯S interactions and C—H⋯O hydrogen bonding. The structural characteristics lead to good second‐order non‐linear optical properties. 相似文献
13.
Andrew Hempel Lilian Y. Y. Ma Arthur Camerman Donald Mastropaolo Norman Camerman 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(12):o681-o682
In the crystal structure of the title dopaminergic compound, C16H24NO2+·Br−·H2O, protonation occurs at the piperidine N atom. The piperidine ring adopts a chair conformation and the cyclohexene ring adopts a half‐chair conformation; together with the planar benzene ring, this results in a relatively planar shape for the whole molecule. Classical hydrogen bonds (N—H⋯Br, O—H⋯Br and O—H⋯O) produce an infinite three‐dimensional network. Hydrogen bonds between water molecules and Br− anions create centrosymmetric rings throughout the crystal structure. Structural comparison of the molecule with the ergoline dopamine agonist pergolide shows that it is the hydrogen‐bond‐forming hydroxy or imino group that is necessary for dopaminergic activity, rather than the presence of a phenyl or a pyrrole ring per se. 相似文献
14.
G. Vasuki S. Thamotharan V. Parthasarathi K. Ramamurthi S. Dubey D. P. Jindal 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):o598-o599
The title compound, C32H45N2O+·Br?·0.5H2O, has the outer two six‐membered rings in chair conformations, while the central ring is in an 8β,9α‐half‐chair conformation. The five‐membered ring of the steroid nucleus adopts a slightly deformed 14α‐envelope conformation. The pyridylmethylene moiety has an E configuration with respect to the hydroxyl group at position 17. The structure is stabilized by a network of O—H?Br‐type intermolecular hydrogen bonds. 相似文献
15.
Zhongshu Li Xiaodan Chen Liu Leo Liu Moritz Theodor Scharnhlz Hansjrg Grützmacher 《Angewandte Chemie (International ed. in English)》2020,59(11):4288-4293
In contrast to cyclic π‐conjugated hydrocarbons, the coordination chemistry of inorganic heterocycles is less developed. Dicarbondiphosphides stabilized by N‐heterocyclic carbenes (NHCs) NHC→C2P2←NHC ( 1 a , b ) (NHC=IPr or SIPr) contain a four‐membered C2P2 ring with an aromatic 6π‐electron configuration. These heterocycles coordinate to a variety of complex fragments with metals from groups 6, 9, and 10, namely [M0(CO)3] (M=Cr, Mo), [CoI(CO)2]+, or [NiIIBr2], through an η4‐coordination mode, leading to complexes 2 a , b , 3 a , b , 5 a , b , and 6 a , b , respectively. These complexes were characterized by X‐ray diffraction methods using single crystals, IR spectroscopy, and DFT calculations. In combination these methods indicate that 1 a , b behave as exceptionally strong 6π‐electron donors. 相似文献
16.
Pavel Kurfürst Jaromír Marek Jn Van
o Jozef Csllei 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(7):o494-o495
The title compound, C21H24FN2O2+·Cl−·C3H8O, is a potential drug designed as a hybrid compound with antihypertensive, antioxidant and β‐adrenolytic activity. The cation contains nearly planar benzofuran and fluorophenyl ring systems, as well as a piperazine ring adopting an almost perfect chair conformation. The benzofuran and piperazine moieties are connected by an ethyl chain, the moieties forming a dihedral angle of 163.12 (13)°. In the crystal structure, ions and propanol solvent molecules are linked via N—H⋯Cl and O—H⋯Cl bonds into linear (010) chains. 相似文献
17.
Antonija Hergold‐Brundi Gordana Pavlovi Ana Dunja Mance Kreimir Jakop
i 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):e520-e521
The title compound, C15H14N2O3, is the first example of a structurally determined tertiary amine with both N‐5‐nitrofurfuryl and N‐prop‐2‐ynyl moieties. The molecule is not planar, i.e. the furan ring is inclined at an angle of 84.35 (4)° to the phenyl ring. The crystal structure is dominated by van der Waals forces. The terminal alkynyl group as the strongest C—H hydrogen‐bond donor is not involved in hydrogen‐bond formation. 相似文献
18.
Lemi Türker 《无机化学与普通化学杂志》2019,645(18-19):1118-1126
Polynitrogen compounds, are rare molecules having only nitrogen atoms. In recent years, they have been considered as promising candidates of clean (green) high energy density materials. They possess high energy content and their sole decomposition product is N2. Presently some prismatic polynitrogen structures (N6 – N14) are considered within the limitations of density functional theory at the levels of B3LYP/6‐311++G(d,p) and B3LYP/cc‐PVTZ. The calculations reveal that they are all highly endothermic but stable. Certain quantum chemical properties, IR and UV/Vis spectra are reported. Homolytic bond cleavage of top rings are considered. Then, the transition state and activation energies, and also homolytic bond dissociation energies for the top rings have been calculated at the level of UB3LYP/6‐311++G(d,p). Also NICS(0) values have been calculated at the level of B3LYP/6‐311++G(d,p). The results indicate that N6 and N10 have aromatic and nonaromatic top (and also base) rings, respectively. All the rest of the structures have antiaromatic rings (all the structures have antiaromatic N4 rings). 相似文献
19.
20.
Vladimir N. Nesterov 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):o806-o809
In the title compound 3,5‐bis(4‐methoxybenzylidene)‐1‐methyl‐4‐piperidone, C22H23NO3, (I), the central heterocyclic ring adopts a flattened boat conformation, while in the related salt 3,5‐bis(4‐methoxybenzylidene)‐1‐methyl‐4‐oxopiperidinium chloride, C22H24NO3+·Cl−, (II), the ring exhibits a `sofa' conformation in which the N atom deviates from the planar fragment. The pendant benzene rings are twisted from the heterocyclic ring planes in both molecules in the same direction, the range of dihedral angles between the ring planes being 24.5 (2)–32.7 (2)°. The dominant packing motif in (I) involves centrosymmetric dimers bound by weak intermolecular C—H⋯O hydrogen bonds. In (II), cations and anions are linked by strong N—H⋯Cl hydrogen bonds, while weak C—H⋯O and C—H⋯Cl hydrogen bonds link the cations and anions into a three‐dimensional framework. 相似文献