Synthesis and Crystal Structure of a New 2D Honeycomb-like Cadmium(II) Complex with Tripodal Ligand

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Syntheses, crystal structures and properties of novel zinc(II) complexes obtained by reactions of zinc(II) malonate with flexible multidentate ligands

Complex [Zn₂(bimb)₂(mal)₂(H₂O)₂]·4H₂O (1) (mal=⁻OCOCH₂COO⁻) was obtained by reaction of bidentate ligand 4,4′-bis(imidazole-1-ylmethyl)biphenyl (bimb) with zinc(II) salt of malonate, while the reaction of the same metal salt with 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (titmb) gives another novel complex [Zn₂(titmb)₂(mal)][mal]·12H₂O (2). The structures of these complexes were determined by X-ray crystallography. The results revealed that 1 is a cyclic dinuclear complex in which the malonate groups act as terminators and prevent further aggregation, while 2 is a 2D honeycomb network in which each independent 2D sheet contains two sub-layers bridged by the malonate groups and complex 2 also contains free malonate as a counteranion connected to the 2D layer by C-H?O hydrogen bonds. The entirely different structure and topology of complexes 1 and 2, on the one hand, indicates that the nature of organic ligands affected the structures of assemblies greatly, and on the other, reveals the versatility of the malonate which can act as a bridging and/or blocking ligand.     

Effects of the intramolecular NH...S hydrogen bond in mononuclear platinum(II) and palladium(II) complexes with 2,2'-bipyridine and benzenethiol derivatives

A series of complexes, [M(bpy)(SAr)2] (M = platinum(II) or palladium(II), bpy = 2,2'-bipyridine, SAr = 2- or 4-(acylamino)benzenethiolate, or 2-(alkylcarbamoyl)benzenethiolate), were synthesized and characterized on the basis of 1H NMR, IR, and electrochemical properties. The structures of [Pt(bpy)(S-2-Ph3CCONHC6H4)2] (1) and [Pt(bpy)(S-2-t-BuNHCOC6H4)2] (3) were determined by X-ray analysis. The complexes have intramolecular NH...S hydrogen bonds between the amide NH group and the sulfur atom. A weak NH...S hydrogen bond in these complexes and [Pd(bpy)(S-2-Ph3CCONHC6H4)2] (4) is detected from the 1H NMR spectra and the IR spectra in chloroform and in the solid state. [Pt(bpy)(S-2-Ph3CCONHC6H4)2] (1) exhibits a remarkably high-energy-shifted lowest-energy band in UV-visible spectra and has a positively shifted oxidation potential. The blue-shift of 42 nm and the positive shift of +0.24 V, as compared to those of [Pt(bpy)(SC6H5)2), are due to the effect of the NH...S hydrogen bond.     

Metal complex with terpyrindine derivative ligand as highly selective colorimetric sensor for iron(Ⅲ)

A new metal complex[MnL₂]（NO₃）₂·CH₃CN（1） was synthesized by reaction of 4’-4-（l,2,4-triazol-l-yl）phenyl -2,2’:6’,2"-terpyridine（L） with manganese nitrate.The structure of the complex was determined by X-ray crystallography.The results of UV-vis studies showed that the complex exhibits colorimetric sensing ability for Fe³⁺,which can be observed by naked eye.     

Construction of Helically Stacked π-Electron Systems in Poly(quinolylene-2,3-methylene) Stabilized by Intramolecular Hydrogen Bonds

π-Stacked polymers, which consist of layered π-electron systems in a polymer, can be expected to be used in molecular electronic devices. However, the construction of a stable π-stacked structure in a polymer is considerably challenging because it requires sophisticated designs and precise synthetic methods. Herein, we present a novel π-stacked architecture based on poly(quinolylene-2,3-methylene) bearing alanine derivatives as the side chain, obtained through the living cyclo-copolymerization of an o-allenylaryl isocyanide. In the resulting polymer, the neighboring quinoline rings of the main chain form a layered structure with π–π interactions, which is stabilized by intramolecular hydrogen bonds. The vicinal quinoline units form two independent helices and the whole molecule is a twisted-tape structure. This structure is established on the basis of UV/CD spectra, theoretical calculations, and atomic-force microscopy.     

Quantitative analysis of inhomogeneous luminance effect on visibility of text

In the present study, we measured the visibility of several types of Japanese text on a liquid crystal display (LCD) with a spatially inhomogeneous luminance and extended the visibility index function (VIF) to explain the current experimental results with a higher degree of accuracy. We quantitatively analyzed the effect of an inhomogeneous luminance, which was produced by the graphical representation of a background without reflected light and by reflected light on a homogeneous background. These results showed that the visibility of text was influenced by the inhomogeneity of the background luminance in a domain that depended on text size. Then we applied a weighted average background luminance with a two dimensional Gaussian function, whose distribution width was related to the text size, to VIF. Finally, we proposed a modified VIF and showed that the new method was able to precisely estimate the actual visibility of text with an inhomogeneous luminance.     

Optical simulation of reduced retinal illuminance caused by senile miosis

In order to simulate elderly vision for young observers, we developed an optical goggle using filters whose transmittance optically simulates the senile miosis: reduction in retinal illuminance as a function of ambient illuminance. First, we measured the pupil size of young and elderly subjects (mean age were 21.8 and 67.1 years, respectively) under six illuminance conditions (from 0.03 to 4850 lx), and formulated the relationship between illuminance and pupillary area functions in both age groups. Next, the transmittance formulae for the filter simulating the senile miosis were derived based on the properties of the pupillary area and visual functions of the elderly and the young subjects including the effect of mydriasis induced by the reduction of light due to the filter in young observers. Finally, we developed a goggle-type simulator using active optical devices which enables young people to experience senile miosis in any environment in real time.     

Transcendence of Certain Reciprocal Sums of Linear Recurrences

 Suppose that {R _n } _n ⩾ 0 is a sequence of integers satisfying a binary linear recurrence relation with suitable conditions. We prove the transcendency of the numbers

Algebraic independence of the values of Mahler functions associated with a certain continued fraction expansion

It is proved that the function , which can be expressed as a certain continued fraction, takes algebraically independent values at any distinct nonzero algebraic numbers inside the unit circle if the sequence {R_k}_k?0 is the generalized Fibonacci numbers.     

Thiophene-fused phospholo[3,2-b]phospholes and their dichalcogenides: Synthesis and structure–photophysical properties relationships

The PCl₃-promoted intramolecular cascade cyclization produced a series of thiophene-fused phospholo[3,2-b]phosphole derivatives, including non-oxidized 2, dioxides 3, and disulfides 4. These derivatives exhibit significantly red-shifted absorptions and fluorescences compared with their benzene-fused analogues. Among the thiophene-fused series, the non-oxidized 2 has the highest fluorescence quantum yield of 0.95. This trend is in contrast to that observed for the benzene analogues, in which a dioxide derivative shows the most intense fluorescence.