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1.
Dr. Feng Wang Martijn A. J. Gillissen Patrick J. M. Stals Dr. Anja R. A. Palmans Prof. Dr. E. W. Meijer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(37):11761-11770
The design of supramolecular motifs with tuneable stability and adjustable supramolecular polymerisation mechanisms is of crucial importance to precisely control the properties of supramolecular assemblies. This report focuses on constructing π‐conjugated oligo(phenylene ethynylene) (OPE)‐based one‐dimensional helical supramolecular polymers that show a cooperative growth mechanism. Thus, a novel set of discotic molecules comprising a rigid OPE core, three amide groups, and peripheral solubilising wedge groups featuring C3 and C2 core symmetry was designed and synthesised. All of the discotic molecules are crystalline compounds and lack a columnar mesophase in the solid state. In dilute methylcyclohexane solution, one‐dimensional supramolecular polymers are formed stabilised by threefold intermolecular hydrogen bonding and π–π interactions, as evidenced by 1H NMR measurements. Small‐angle X‐ray and light scattering measurements reveal significant size differences between the columnar aggregates of C3‐ and C2‐symmetrical discotics, that is, the core symmetry strongly influences the nature of the supramolecular polymerisation process. Temperature‐dependent CD measurements show a highly cooperative polymerisation process for the C3‐symmetrical discotics. In contrast, the self‐assembly of C2‐symmetrical discotics shows a smaller enthalpy release upon aggregation and decreased cooperativity. In all cases, the peripheral stereogenic centres induce a preferred handedness in the columnar helical aggregates. Moreover, one stereogenic centre suffices to fully bias the helicity in the C2‐symmetrical discotics. Finally, chiral amplification studies with the C3‐symmetrical discotics were performed by mixing chiral and achiral discotics (sergeants‐and‐soldiers experiment) and discotics of opposite chirality (majority‐rules experiment). The results demonstrate a very strong sergeants‐and‐soldiers effect and a rather weak majority‐rules effect. 相似文献
2.
《Journal of computational chemistry》2018,39(20):1498-1507
Global exploration of equilibrium structures and interconversion pathways on the quantum chemical potential energy surface (PES) is performed for (H2CO)n (n = 2–4) by using the Scaled Hypersphere Search‐Anharmonic Downward Distortion Following (SHS‐ADDF) method. Density functional theoretical (DFT) calculations with empirical dispersion corrections (D3) yielded comparable results for formaldehyde dimer in comparison with recent detailed studies at CCSD(T) levels. Based on DFT‐D3 calculations, trimer and tetramer structures and their stabilities were studied. For tetramer, a highly symmetrical S4 structure was found as the most stable form in good accordance with experimentally determined tetramer unit in the formaldehyde crystal. © 2018 Wiley Periodicals, Inc. 相似文献
3.
Structure and Bonding in Bis(1‐naphthyl) Diselenide and Bis{[2‐(N,N‐dimethylamino)methyl]phenyl} Tetraselenide,and Their Brominated Derivatives
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Esther M. Takaluoma Teemu T. Takaluoma Raija Oilunkaniemi Risto S. Laitinen 《无机化学与普通化学杂志》2015,641(5):772-779
The formation and crystal structures of bis(1‐naphthyl) diselenide ( 1 ) and bis{[2‐(N,N‐dimethylamino)methyl]phenyl} tetraselenide ( 2 ) are described. Whereas 1 can be produced in good yields, 2 is formed only as a minor product together with the known main product, bis{[2‐(N,N‐dimethylamino)methyl]phenyl} diselenide. The composition of the reaction mixture is semi‐quantitatively estimated by 77Se NMR spectroscopy and DFT calculations. The effect of the n2→σ*(Se–Se) and π→σ*(Se–Se) secondary bonding interactions on the Se–Se bonds is discussed both by DFT calculations and comparison with literature, as available. The bromination of 1 yields monomeric (1‐naphthyl)selenenyl bromide ( 3 ) in good yields. That of the reaction mixture of (C6H4CH2NMe2)Sex (x = 2–4) and Se8 afforded (C6H4CH2NMe2H)2[SeBr4] ( 4 ) and (C6H4CH2NMe2H)2[SeBr6] ( 5 ) in addition to (C6H4CH2NMe2)SeBr, which has been previously reported. 相似文献
4.
The self‐complementary tetrameric propargyl triols 8, 14, 18 , and 21 were synthesized to investigate the duplex formation of self‐complementary, ethynylene‐linked UUAA, AAUU, UAUA, and AUAU analogues with integrated bases and backbone (ONIBs). The linear synthesis is based on repetitive Sonogashira couplings and C‐desilylations (34–72% yield), starting from the monomeric propargyl alcohols 9 and 15 and the iodinated nucleosides 3, 7, 11 , and 13 . Strongly persistent intramolecular H‐bonds from the propargylic OH groups to N(3) of the adenosine units prevent the gg‐type orientation of the ethynyl groups at C(5′). As such, an orientation is required for the formation of cyclic duplexes, this H‐bond prevents the formation of duplexes connected by all four base pairs. However, the central units of the UAUA and AAUU analogues 18 and 14 associate in CDCl3/(D6)DMSO 10 : 1 to form a cyclic duplex characterized by reverse Hoogsteen base pairing. The UUAA tetramer 8 forms a cyclic UU homoduplex, while the AUAU tetramer 21 forms only linear associates. Duplex formation of the O‐silylated UUAA and AAUU tetramers is no longer prevented. The self‐complementary UUAA tetramer 22 forms Watson–Crick‐ and Hoogsteen‐type base‐paired cyclic duplexes more readily than the sequence‐isomeric AAUU tetramer 23 , further illustrating the sequence selectivity of duplex formation. 相似文献
5.
Tiina Maaninen Heikki M. Tuononen Katja Kosunen Raija Oilunkaniemi Johanna Hiitola Risto Laitinen Tristram Chivers 《无机化学与普通化学杂志》2004,630(12):1947-1954
Supermesityl selenium diimide [Se{N(C6H2tBu3‐2, 4, 6)}2; Se{N(mes*)}2] can be prepared in a good yield from the reaction of SeCl4 and (mes*)NHLi. The molecule adopts an unprecedented anti, anti‐conformation, as deduced by DFT calculations at PBE0/TZVP level of theory and supported by 77Se NMR spectroscopy and a crystal structure determination. An analogous reaction involving (C6H2Me3‐2, 4, 6)NHLi [(mes)NHLi] unexpectedly lead to the reduction of selenium and afforded the selenium diamide Se{NH(mes)}2 that was characterized by X‐ray crystallography and 77Se NMR spectroscopy. The Se‐N bonds of 1.847(3) and 1.852(3) Å show normal single bond lengths. The <NSeN bond angle of 109.9(1)° also indicates a tetrahedral AX2E2 bonding arrangement around selenium. Two N‐H···N hydrogen bonds link the Se{NH(mes)}2 molecule with two discrete (mes)NH2 molecules. In the solid state selenium diamide adopts the anti‐conformation, whereas in solution the presence of both syn‐ and anti‐isomers could be observed. PBE0/TZVP calculations of the shielding tensors of 28 different types of selenium‐containing molecules, for which the 77Se chemical shifts are unambiguously known, were carried out to assist the spectral assignment of Se{N(mes*)}2 and Se{NH(mes)}2. 相似文献
6.
Bernard Boitrel Valrie Baveux‐Chambenoît Philippe Richard 《Helvetica chimica acta》2004,87(9):2447-2464
The syntheses of various strapped and ‘picket‐fence’ chiral porphyrins are described, and their reactivities towards the enantioselective epoxidation of alkenes are reported. Four L ‐proline residues provide the chirality for the various meso‐substituted catalysts, which differ by either the spatial arrangement of the stereogenic centers or the nature and length of the straps. The resulting bridged structures possess four amide linkages in each strap, leading to highly rigid molecules with well‐defined geometries whereas the strapped Fe catalysts gave rise to only moderate enantioselectivities, the C2‐symmetrical ones being superior to the D2‐symmetrical compounds. The D2‐symmetrical ‘picket‐fence’ porphyrins were as selective as their strapped counterparts. 相似文献
7.
New Polydentate Trimethylsilyl Chalcogenide Reagents for the Assembly of Polyferrocenyl Architectures
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Mahmood Azizpoor Fard Bahareh Khalili Najafabadi Mahdi Hesari Prof. Dr. Mark S. Workentin Prof. Dr. John F. Corrigan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7037-7047
A series of polychalcogenotrimethylsilane complexes Ar(CH2ESiMe3)n, (Ar=aryl; E=S, Se; n=2, 3, and 4) can be prepared from the corresponding polyorganobromide and M[ESiMe3] (M=Na, Li). These represent the first examples of the incorporation of such a large number of reactive ?ESiMe3 moieties onto an organic molecular framework. They are shown to be convenient reagents for the preparation of the polyferrocenylseleno‐ and thioesters from ferrocenoyl chloride. The synthesis, structures, and spectroscopic properties of the new silyl chalcogen complexes 1,4‐(Me3SiECH2)2(C6Me4) (E=S, 1 ; E=Se, 2 ), 1,3,5‐(Me3SiECH2)3(C6Me3) (E=S, 3 ; E=Se, 4 ) and 1,2,4,5‐(Me3SiECH2)4(C6H2) (E=S, 5 ; E=Se, 6 ) and the polyferrocenyl chalcogenoesters [1,4‐{FcC(O)ECH2}2(C6Me4)] (E=S, 7 ; E=Se, 8 ), [1,3,5‐{FcC(O)ECH2}3(C6Me3)] (E=S, 9 ; E=Se, 10 ) and [1,2,4,5‐{FcC(O)ECH2}4(C6H2)] (E=S, 11 illustrated; E=Se, 12 ) are reported. The new polysilylated reagents and polyferrocenyl chalcogenoesters have been characterized by multinuclear NMR spectroscopy (1H, 13C, 77Se), electrospray ionization mass spectrometry and, for complexes 1 , 2 , 3 , 4 , 7 , 8 , and 11 , single‐crystal X‐ray diffraction. The cyclic voltammograms of complexes 7 – 11 are presented. 相似文献
8.
Synthesis,Photophysical and Electrochemical Properties of Amide‐Linked Phthalocyanine‐Fullerene Dyad
Haiying Zhao Zhibo Liu Xiaoliang Zhang Jianguo Tian Chen Chen Yizhou Zhu Jianyu Zheng 《中国化学》2012,30(8):1766-1770
A new amide‐linked phthalocyanine‐fullerene dyad ZnPc‐C60 was synthesized and characterized. The photophysical and electrochemical properties of the ZnPc‐C60 dyad were investigated. The fluorescence spectrum and quantum yield in different solvents showed the occurrence of photoinduced electron transfer (PET) from the singlet excited ZnPc to C60, which was further confirmed by nanosecond transient absorption spectra and cyclic voltammetry data. The free energy change for charge separation (ΔGCS) was estimated to be exothermic with ?0.51 eV, which favored the formation of charge‐separation state. The PET from ZnPc to C60 in ZnPc‐C60 made the dyad exhibit stronger reverse saturable absorption performance compared with C60 and the control sample in the Z‐scan experiments, which indicated the synergistic effect of two active moieties in the dyad. 相似文献
9.
Mutai Bao Maochun Hong Weiping Su Rong Cao 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):e219-e220
The polyseleno title compound, bis(N,N‐diethylselenocarbamoyl) triselenide, [(Se2CNEt2)2Se] or C10H20N2Se5, is obtained from the disproportion of sodium N,N‐diethyl‐1,1‐diselenocarbamate. An Se atom connects two N,N‐diethyl‐1,1‐diselenocarbamate groups with Se—Se distances in the range 2.4500 (11)–2.8601 (12) Å 相似文献
10.
Photoinduced electron transfer(PET) processes between C60-C6H8SO and Tetrathiafulvalene(TTF) have been studied by nanosecond laser photolysis.Quantrm yiekds(φet) and rate constants of electron transfer(ket) from TTF to excited triplet state of[60] fullerene-containing cyclic sulphoxide in benzonitrile(BN) have been evaluated by observing the transient absorption bands in the NIR region.With the decay of excited triplet state of [60]fullerene-containing cyclic suplhoxide,the rise of radical anion of [60]fullerene-containing cyclic sulphoxinde is observed. 相似文献
11.
Wade L. Davis Alfred Muller 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(9):1310-1318
The crystal structures of SeP(o‐tol)R2, where o‐tol is ortho‐tolyl (2‐methylphenyl) and R is Ph (phenyl), namely (2‐methylphenyl)diphenylphosphane selenide, C19H17PSe, or Cy (cyclohexyl), namely dicyclohexyl(2‐methylphenyl)phosphane selenide, C19H29PSe, were determined to aid in the evaluation of the steric and electronic behaviour of these analogous phosphane compounds. The compounds crystallized in similar monoclinic crystal systems, but are differentiated in their unit cells by a doubling of the number of independent molecules for R = Cy (Z′ = 2) and the choice of glide plane by convention. The preferred orientation for the o‐tolyl substituent obtained from the X‐ray structural analysis is gauche for R = Ph and anti for R = Cy (using the Se—P—Cipso—Cortho torsion angles as reference). Density functional theory (DFT) calculations showed both conformations to be equally probable and indicate that the preferred solid‐state conformer is probably due to the minimization of repulsion energies, resulting in a packing arrangement primarily featuring weak C—H…Se interactions and additional C—H…π interactions in the R = Ph structure. A detailed electronic and steric analysis was conducted on both phosphanes using Se—P bond lengths, multinuclear NMR 1JSe–P coupling constants, theoretical topological evaluation and crystallographic and solid‐angle calculations, and compared to selected literature examples. The results indicate that the use of the o‐tolyl substituent increases both the electron‐donating capability and the steric size, but is also dependent on whether the o‐tolyl group adopts a gauche or anti conformation. The single‐crystal geometrical data are unable to detect electronic differences between these two structures due to the somewhat large displacement parameters observed for the Se atom in the R = Cy structure. 相似文献
12.
《化学:亚洲杂志》2017,12(14):1824-1835
An adaptable cyclic porphyrin dimer with highly flexible linkers has been used as an artificial molecular container that can efficiently encapsulate various aromatic guests (TCNQ/C60/C70) through strong π–π interactions by adjusting its cavity size and conformation. The planar aromatic guest (TCNQ) can be easily and selectively exchanged with larger aromatic guests (C60/C70). During the guest‐exchange process, the two porphyrin rings switch their relative orientation according to the size and shape of the guests. This behavior of the cyclic container has been thoroughly investigated by using UV/Vis spectroscopy, NMR spectroscopy, and X‐ray crystal structure determination of the host–guest assemblies. The electrochemical and photophysical studies demonstrated the occurrence of photoinduced electron transfer from bisporphyrin to TCNQ/C60/C70 in the respective host–guest assemblies. The cyclic host can form complexes with C60 and C70 with association constants of (2.8±0.2)×105 and (1.9±0.3)×108 m −1, respectively; the latter value represents the highest binding affinity for C70 reported so far for zinc(II) bisporphyrinic receptors. This high selectivity for the binding of C70 versus C60 allows the easy extraction and efficient isolation of C70 from a C60/C70 fullerene mixture. Experimental evidence was substantiated by DFT calculations. 相似文献
13.
Sari M. Kunnari Raija Oilunkaniemi Risto S. Laitinen Markku Ahlgren 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):o610-o611
The novel title tetraselenacalix[4]arene, C16H8S4Se4 or [(C4H2S)Se]4, has a centrosymmetric cyclic molecular structure with approximate C2h molecular symmetry. The four thienyl rings are joined together by Se bridges and exhibit a syn–syn–anti–anti arrangement around the molecule. The lattice consists of skewed stacks of molecules, with chalcogen–chalcogen close contacts binding the stacks together, forming a two‐dimensional network of molecules. 相似文献
14.
A New Approach for the Photosynthetic Antenna–Reaction Center Complex with a Model Organized Around an s‐Triazine Linker
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Susanne Kuhri Dr. Georgios Charalambidis Prof. Panagiotis A. Angaridis Prof. Theodore Lazarides Dr. Georgia Pagona Dr. Nikos Tagmatarchis Prof. Dr. Athanassios G. Coutsolelos Prof. Dr. Dirk M. Guldi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):2049-2057
Two new artificial mimics of the photosynthetic antenna‐reaction center complex have been designed and synthesized (BDP‐H2P‐C60 and BDP‐ZnP‐C60). The resulting electron‐donor/acceptor conjugates contain a porphyrin (either in its free‐base form (H2P) or as Zn‐metalated complex (ZnP)), a boron dipyrrin (BDP), and a fulleropyrrolidine possessing, as substituent of the pyrrolidine nitrogen, an ethylene glycol chain terminating in an amino group C60‐X‐NH2 (X=spacer). In both cases, the three different components were connected by s‐triazine through stepwise substitution reactions of cyanuric chloride. In addition to the facile synthesis, the star‐type arrangement of the three photo‐ and redox‐active components around the central s‐triazine unit permits direct interaction between one another, in contrast to reported examples in which the three components are arranged in a linear fashion. The energy‐ and electron‐transfer properties of the resulting electron‐donor/acceptor conjugates were investigated by using UV/Vis absorption and emission spectroscopy, cyclic voltammetry, and femtosecond transient absorption spectroscopy. Comparison of the absorption spectra and cyclic voltammograms of BDP‐H2P‐C60 and BDP‐ZnP‐C60 with those of BDP‐H2P, BDP‐ZnP and BDP‐C60, which were used as references, showed that the spectroscopic and electrochemical properties of the individual constituents are basically retained, although some appreciable shifts in terms of absorption indicate some interactions in the ground state. Fluorescence lifetime measurements and transient absorption experiments helped to elucidate the antenna function of BDP, which upon selective excitation undergoes a rapid and efficient energy transfer from BDP to H2P or ZnP. This is then followed by an electron transfer to C60, yielding the formation of the singlet charge‐separated states, namely BDP‐H2P .+‐ C60 .? and BDP‐ZnP .+‐ C60 . ?. As such, the sequence of energy transfer and electron transfer in the present models mimics the events of natural photosynthesis. 相似文献
15.
Prof. Dr. Long‐Li Lai Shun‐Ju Hsu Hui‐Chu Hsu Sheng‐Wei Wang Dr. Kung‐Lung Cheng Chun‐Jung Chen Tsai‐Hui Wang Prof. Dr. Hsiu‐Fu Hsu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(21):6542-6547
Two series of unconventional triazine‐based dendrimers with C2 symmetry and C3 symmetry were prepared. The newly prepared C3‐symmetrical dendrimers were characterized by 1H and 13C NMR spectroscopy, mass spectrometry, and elemental analysis. Differential scanning calorimetry, polarizing microscopy, and powder XRD showed that the C3‐symmetrical dendrimers display columnar liquid‐crystalline phases during thermal treatment, but the C2‐symmetrical dendrimers were not observed to behave correspondingly. The molecular conformations of C3‐ and C2‐symmetrical dendrimers were obtained by computer simulation with the MM2 model of the CaChe program in the gas phase. The simulation results reasonably explain the different mesogenicities of C3‐ and C2‐symmetric dendrimers. This new strategy should be applicable to other types of unconventional dendrimers with rigid frameworks for displaying columnar liquid‐crystalline behavior. 相似文献
16.
Yiyu Zhan Zhengbiao Zhang Xiangqiang Pan Jian Zhu Nianchen Zhou Xiulin Zhu 《Journal of polymer science. Part A, Polymer chemistry》2013,51(7):1656-1663
A cyclic selenium‐based reversible addition‐fragmentation chain transfer (RAFT) agent, 5,5‐dimethyl‐3‐phenyl‐2‐selenoxo‐1,3‐selenazolidin‐4‐one (RAFT‐Se), was synthesized and utilized in the RAFT polymerizations of vinyl acetate (VAc). Its analog, 5,5‐dimethyl‐3‐phenyl‐2‐thioxothiazolidin‐4‐one (RAFT‐S), was also used in RAFT polymerizations for comparison under identical conditions. The RAFT polymerizations of VAc with RAFT‐Se were moderately controlled evidenced by the increase of molecular weights with conversion, despite the slightly high Mw/Mn (less than 1.90), whereas the molecular weights were poorly controlled in the presence of RAFT‐S (2.00 < Mw/Mn < 2.30). Thanks to its unusual cyclic structure of RAFT‐Se, one or more RAFT‐Se species was incorporated into the resultant poly(VAc) as revealed by the results of cleavage of polymer and atomic absorption spectroscopy. Considering the biorelated functions of both poly(VAc) and Se element, this work undoubtedly provided a successful methodology of how to incorporate high content of Se into a molecular weight controlled poly(VAc). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
17.
Frank Hörmann Prof. Dr. Andreas Hirsch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):3188-3197
We report here on the facile synthetic access of a new family of bis‐, tetra‐, hexa‐, and heptafullerenes (prototypes I–IV), which can be easily converted into very water soluble polyelectrolytes with up to 60 charges located on their periphery. Their very regioselective formation is based on the use of C2v‐symmetrical pentakisadducts 3 and hexakisadducts 2 as key intermediates. All fullerene moieties incorporated in these macromolecular structures involve a complete or partial octahedral addition pattern. Tripod‐shaped tetrafullerenes 9 a , b (type II), which can accumulate up to thirty positive or negative charges, are very soluble in acidic or basic water, respectively. Hexafullerenes 13 a , b (type III) were synthesized via isoxazolinofullerenes 10 followed by photolytic cleavage of the isoxazoline group. The giant heptafullerene 1 b (type IV) representing the anionic counterpart of the previously synthesized polyelectrolyte 1 a can store up to 60 negative charges on its periphery within a defined three‐dimensional structure. We also discovered a new cyclopropanation reaction of C60 involving dibromomalonates and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU). This reaction allows even for the highly regioselective formation of hexakisadducts with an octahedral addition pattern without requiring activation with reversibly binding addends such as 9,10‐dimethylanthracene (DMA). 相似文献
18.
Shin‐Ichi Yusa Shigeki Awa Masanori Ito Takeshi Kawase Tadao Takada Kenichi Nakashima Dian Liu Shigeru Yamago Yotaro Morishima 《Journal of polymer science. Part A, Polymer chemistry》2011,49(13):2761-2770
Water‐soluble diblock copolymer, poly(N‐isopropylacrylamide)‐block‐poly(N‐vinyl‐2‐pyrroridone) (PNIPAMm‐b‐PNVPn), was found to associate with fullerene (C60), and thus C60 can be solubilized in water. The 63C60/PNIPAMm‐b‐PNVPn micelle formed a core‐shell micelle‐like aggregate comprising a C60/PNVP hydrophobic core and a thermoresponsive PNIPAM shell. The C60‐containing polymer micelle formation and its thermoresponsive behavior were characterized using light scattering and 1H NMR techniques. The hydrodynamic radius (Rh) of the C60‐bound polymer micelle increased with increasing temperature, which was ascribed to the hydrophobic association between dehydrated PNIPAM shells above lower critical solution temperature (LCST). 1H NMR data suggest that the motion of the PNIPAM block is restricted above LCST due to the dehydration of the PNIPAM shell in water. The generation of singlet oxygen by photosensitization by the C60‐bound polymer micelle was confirmed from photooxidation of 9,10‐anthracenedipropionic acid. Furthermore, DNA was found to be cleaved by visible light irradiation in the presence of the C60‐bound polymer micelle. Therefore, there may be a hope for a pharmaceutical application of the C60‐bound polymer micelle to cancer photodynamic therapy. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011. 相似文献
19.
David B. Cordes Guoxiong Hua Alexandra M. Z. Slawin J. Derek Woollins 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(12):o509-o514
Two polymorphs of 2,5‐diphenyl‐1,3,4‐selenadiazole, C14H10N2Se, denoted (Ia) and (Ib), and a new polymorph of 2,5‐bis(thiophen‐2‐yl)‐1,3,4‐selenadiazole, C10H6N2S2Se, (IIb), form on crystallization of the compounds, prepared using Woollins' reagent (2,4‐diphenyl‐1,3‐diselenadiphosphetane 2,4‐diselenide). These compounds, along with 2‐(4‐chlorophenyl)‐5‐phenyl‐1,3,4‐selenadiazole, C14H9ClN2Se, (III), and 2‐(furan‐2‐yl)‐5‐(p‐tolyl)‐1,3,4‐selenadiazole, C13H10N2OSe, (IV), show similar intermolecular interactions, with π–π stacking, C—H...π interactions and weak hydrogen bonds typically giving rise to molecular chains. However, the combination of interactions differs in each case, giving rise to different packing arrangements. In polymorph (Ib), the molecule lies across a crystallographic twofold rotation axis, and (IV) has two independent molecules in the asymmetric unit. 相似文献
20.
Organoselenium compounds containing pyrazole or phenylthiazole groups: Synthesis,structure, tin(IV) complexes and antiproliferative activity
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The diorganodiselenides (pzCH2CH2)2Se2 ( 1 ) and (PhtzCH2)2Se2 ( 2 ) were prepared by reacting Na2Se2 with 1‐(2‐bromoethyl)‐1H‐pyrazole and 4‐(chloromethyl)‐2‐phenylthiazole, respectively, while the reactions between 1‐(2‐bromoethyl)‐1H‐pyrazole or 4‐(chloromethyl)‐2‐phenylthiazole and the lithium organoselenolates [2‐(Et2NCH2)C6H4]SeLi and [2‐{O(CH2CH2)2NCH2}C6H4]SeLi in a 1:1 molar ratio resulted in the heteroleptic diorganoselenium(II) compounds [2‐(Et2NCH2)C6H4](R)Se (R = pzCH2CH2 ( 3 ) or PhtzCH2 ( 5 )) and [2‐{O(CH2CH2)2NCH2}C6H4](R)Se (R = pzCH2CH2 ( 4 ) or PhtzCH2 ( 6 )). The diorganotin(IV) bis(organoselenolato) derivatives of type R2Sn(SeCH2CH2pz)2 (R = 2‐(Me2NCH2)C6H4 ( 7 ) or Me ( 8 )) were obtained by reacting (pzCH2CH2)SeNa with the appropriate diorganotin(IV)dichloride in a 2:1 molar ratio. All compounds were investigated using NMR spectroscopy (1H, 13C, 77Se, 119Sn as appropriate) and ESI+ mass spectrometry. The molecular structures of 2 and 6 were determined using single‐crystal X‐ray diffraction. The formation of a 10–Se–3 hypercoordinated species was evidenced for 6 in the solid state, as a consequence of the C,N coordination behaviour of the 2‐{O(CH2CH2)2NCH2}C6H4 group. Compounds 1 , 7 and 8 were investigated for their antiproliferative activity towards the mouse colon carcinoma C26 cell line with the preliminary results showing a better activity than 5‐fluorouracil. 相似文献