CNDO/BW study of prototropy in 2-acetyl-1,3-indandione

Conclusions CNDO/BW methods have been used to determine optimal conformations of potentially prototropic forms of 2-acetyl-1,3-indandione and optimal paths for intramolecular proton transfer within the molecule. Possible mechanisms for external prototropy are discussed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1747–1751, August, 1981.     

自组装膜

自动形成有序有机薄膜可通过自组装(SA)技术得到.SA成膜技术快速简便, SA膜对热, 时间, 化学环境及外压稳定, 有较高的二维或三维有序性, 是获得超晶格有序材料的一种有效方法, 在非线性光学, 分子器件, 分子生物学及表面材料工程中都有潜在的应用前景.     

Imino-enamine tautomerism and dynamic prototropy in 1-imino-3-amino-1H-indens

The tautomeric structures and dynamic prototropic behavior of the products 1 and 2 obtained in the condensation reaction of 1,3-indandione and 2-pyridyl-1,3-indandione with p-toluidine, respectively, were investigated by ¹H NMR spectroscopy and X-ray analysis. In the solid state, compound 1 is in an imino-enamine tautomeric form, whereas in solution it coexists with an imino-imino tautomeric form. Dynamic 1,5-prototropic interconversion of the imino-enamine form was revealed to be very fast at room temperature by temperature-dependent ¹H NMR spectra. For 2, the imino-enamine form is the only species present in solution. The hydrogen of the enamine NH is hydrogen-bonded intramolecularly with the nitrogen in the pyridine ring. When the temperature is raised, the NH proton enters into dynamic 1,5-migration, which is accompanied by internal rotation around the pivot bond, which changes the hydrogen-bonding sites. For the condensation product 3 of 2-(2-quinolyl)-1,3-indandione with p-butylaniline, dynamic behavior similar to that found in 2 was observed also in ¹³C NMR spectra.     

Self-assembly molecular architectures with novel cyclic dimers

Highly emissive conjugated compounds containing pyridine (or pyrimidine) and cyano ligands have been synthesized by palladium-catalyzed cross-coupling reaction. These ligands readily react with Re(CO)₃(THF)₂Br to form cyclic supramolecules by self-assembly processes. At room temperature these supramolecules are emissive, and the emission is ligand-localized, as evidenced from the Stokes shift and the lifetime data.     

Structure dependent prototropy in 4-hydroxy-3-formylideneamino-1-methyl/phenylquinolin-2-ones

The electronic absorption spectra of 4-hydroxy-3-formyl quinolin-2-ones and their Schiff bases were investigated in various solvents of varying polarity. The three aromatic transitions of napthalene in quinolin-2-one are shifted to longer wavelength on their transformation to anils. Electron-donating group in the anils lead to enolimine form, while electron-withdrawing group leads to an equilibrium mixture of enolimine and ketoamine forms and the Schiff base derived from alkyl amine exist in ketoamine form. The prototropic interconversion of enolimine and ketoimine forms in the anils with the electron-withdrawing substituted anils is further supported by proton NMR studies. The spectral shifts are solvent dependent. Dipolar aprotic solvents bring bathochromic shift while polar protic solvents cause blue shift in the longer wavelength absorption maxima. In the case of Schiff bases substituted by electron-donating group the bathochromic shift is directly related to the polarity of the solvents.     

Self-assembly in glycolipids

The interest in the glyco-world is widespread and covers quite a number of different areas. We restrict ourselves to underline some features concerning interactions and organization in the hydrophilic region of glycolipid aggregates that, besides the biological or technological aspects, constitute an experimental and theoretical challenge, as they invest some aspects of colloidal self-assembly that keep on being not completely understood.     

Self-assembly sodalite-like framework

The dense packing of shape complementary N-donor molecules dominates the self-assembly of coordination polymers possessing sodalite-like topology and supports nanosize molecular cages.     

Self-assembly of heterogeneous supramolecular structures with uniaxial anisotropy

Uniaxial anisotropy in two-dimensional self-assembled supramolecular structures is achieved by the coadsorption of two different linear molecules with complementary amine and imide functionalization. The two-dimensional monolayer is defined by a one-dimensional stack of binary chains, which can be forced to line up along steps in vicinal surfaces. The competing driving forces in the self-organization process are discussed in light of the structures observed during single molecule adsorption and coadsorption on flat and vicinal surfaces and the corresponding theoretical calculations.     

Self-assembly with postmodification: kinetically stabilized metalla-supramolecular rectangles

Interaction of a predesigned molecular "clip" (4) with rigid dipyridyl bridging ligands, in acetone/water mixtures, leads to the formation of molecular rectangles (5-8) in 92-97% isolated yields via spontaneous self-assembly. Characterization was accomplished with multinuclear NMR and UV-vis spectroscopy, FAB mass spectrometry, and X-ray crystallography. The length of these metallamacrocycles ranges from 2 to 3 nm. Postmodification via non-nucleophilic counterion exchange results in enhanced structural integrity for the assemblies.     

腺嘌呤取代锌卟啉配合物的自组装研究

合成了一种新型的带有腺嘌呤取代基的锌卟啉并对其进行了表征。结果表明,腺嘌呤取代基与中心金属锌的轴向配位驱动了自组装。分子量的测量及紫外可见和荧光光谱表明,存在由自组装而产生的卟啉低聚物。     

Self-assembly of fullerene-rich nanostructures with a stannoxane core

Fullerene derivatives bearing a carboxylic acid function undergo self-assembly with n-butylstannonic acid (nBuSn(O)OH) to produce fullerene-rich nanostructures with a stannoxane core in almost quantitative yields.     

Self-assembly of Micrometer-long DNA Nanoribbons with Four Oligonucleotides

DNA nanostructures have found widespread applications in areas including nanoelectronics and biomedicine. However, traditional DNA origami needs a long single‐stranded virus DNA and hundreds of short DNA strands, which make this method complicated and money‐consuming. Here, we present a protocol for the assembly of DNA nanoribbons with only four oligonucleotides. DNA nanoribbons with different dimensions were successfully assembled with a 96‐base scafford strand and three short staples. These biotinylated nanoribbons could also be decorated with streptavidins. This approach suggests that there exist great design spaces for the creation of simple nucleic acid nanostructures which could facilitate their application in plasmonic or drug delivery.     

Opto-thermal reorientation of nematics with two-fold degenerate alignment

The preferred direction of alignment of the liquid crystal molecules in nematics with two-fold degenerate alignment can be affected substantially by changing the temperature or by applying an electric field. As a result, an almost in-plane switching of the molecules occurs. Here, we report an opto-thermal reorientation effect in a nematic with two-fold degenerate alignment due to a local heating of the liquid crystal by a high power laser beam. The mechanism of this phenomenon is discussed. The opto-thermal reorientation of the molecules makes it possible to visualize the temperature distribution in the illuminated cell and some applications can be foreseen.     

Self-assembly of bridged silsesquioxanes incorporated with conjugated organic functionalities

Self-assembly of bridged silsesquioxanes with a chemical structure of (RO)₃Si-R′-Si(OR)₃ represents an efficient approach to design and to fabricate functional organic/inorganic nanocomposites. The desired functionalities are mainly incorporated into the R′ with R of a hydrolysable alkoxide group such as CH₃ or CH₃CH₂. This feature article discusses two typical assembly approaches: self-directed assembly aiming at ordered solid materials and surfactant-directed assembly aiming at periodic mesoporous organosilica, with emphasis on the bridged silsesquioxanes in which conjugated functional organic groups are incorporated. The conjugated moieties are shown to be critical to the resulting assembly structure, morphology, and property. Self-assembly of three bridged silsesquioxanes based on polydiacetylene, perylene, and porphyrin has been detailed, respectively.     

Self-assembly reactions with a bis(benzene-o-dithiolato) ligand

Reaction of the 1,5-diamidonaphthalene bridged bis(benzene-o-dithiol) ligand H4- with Ti4+ leads to the unexpected formation of a dinuclear meso-complex anion [Ti2(B)3](4-), while the catechol analog H(4-) has been reported to yield the tetrahedral [M4(A)6](8-) cluster.     

Self-assembly to monolayer graphene film with high electrical conductivity

Monolayer chemically converted graphene (CCG) nanosheets can be homogeneously self-assembled onto silicon wafer modified by 3-aminopropyl triethoxysilane (APTES) to form very thin graphene film. The CCG film was characterized by FT-IR, XRD, SEM, TEM and AFM. Results show that CCG sheets formed monolayer film after assembled onto silicon wafer and there is a very tight chemical bond between sheets and wafer. Furthermore, the electrical measurements revealed that the monolayer graphene film has an excellent electrical conductivity.     

多碘阴离子与双核配合物阳离子的超分子组装

通过多碘阴离子与双核配合物阳离子的超分子组装获得了3个新的化合物并对其进行了X射线结构测定和红外光谱,紫外-可见光谱的表征。它们是[(NiCl(bpy)~2)~2^2^+](I~3^-)~2(I~2)(1),[(MnCl(bpy)~2)~2^2^+](I~3^-)~2(I~2)(2)和[(MnCl(bpy)~2)~2^2^+](I~7^-)~1~/~2(I~5^-)(I~3^-)~1~/~2(I~2)~1~/~2(bpy=2,2'-bipyridine)(3)。晶体学数据：1单斜晶系,空间群C2/c,a=1.37091(3)nm,b=1.67996(3)nm,c=2.20708(5)nm,β=91.6114(12)°,V=5.08106(18)nm^3,Z=4,对4367个可观测反射点R1=0.0674;2单斜晶系,空间群C2/c,a=1.38898(3)nm,b=1.70579(4)nm,c=2.22092(4)nm,β=92.9168(13)°,V=5.25523(19),Z=4,对4485个可观测反射点R1=0.0470;3三斜晶系,空间群P-1,a=1.10793(4)nm,b=1.43488(5)nm,c=1.98724(8)nm,α=100.6352(16)°,β=96.4348(19)°,γ=110.0297(19)°,V=2.86409(18)nm^3,Z=2,对7156个可观测反射点R1=0.0634。这三个化合物中都含有具有分叉形状的双核配合物阳离子[(MCl(bpy)~2)~2]^2^+(M=Mn,Ni),它们通过配体bpy之间的π-π堆垛构成带孔洞的层状结构,在层中由配体bpy围成的孔洞填充了I~2分子或I~3^-阴离子,组装成由I~2分子或I~3^-阴离子穿越的正电性的层。在层和层之间则占据了相互连接的I~2,I~3^-,I~5^-,I~7^-,并与层中的I~2,I~3^-相连,形成复杂的具有无限扩展结构的多碘离子的网络,在网络中,多碘离子构成了直径达纳米的孔道结构。对化合物的红外光谱(4000～50cm^-^1)进行了归属。化合物1和3的紫外-可见漫反射光谱(200～800nm)为无特征的宽吸收带,源于无限扩展结构的多碘离子上的电子离域。