Steady state and time-resolved spectroscopic investigations on the photoreactions involved within the electronically excited electron acceptor 9-cyanoanthracene in presence of benzotriazole and benzimidazole donors

The electrochemical, “steady-state” and “time-resolved” spectroscopic investigations were made on the well-known electron acceptor 9-cyanoanthracene (CNA) when interacted with the electron donors benzotriazole (BZT) and benzimidazole (BMI) molecules. Though electrochemical measurements indicate the thermodynamical possibility of occurrences of photoinduced electron transfer reactions within these reacting systems in the lowest excited singlet state (S₁) of the acceptor CNA but the steady-state and time-resolved measurements clearly demonstrate only the triplet-initiated charge separation reactions. It was reported earlier that in the cases of disubstituted indole molecules the occurrences of photoinduced electron transfer reactions were apparent both in the excited singlet and triplet states of the acceptor 9-cyanoanthracene, but the similarly structured present donor molecules benzotriazole (and benzimidazole) behave differently from indoles. The weak ground state complex formations within the presently studied reacting systems appear to be responsible for the observed static quenching phenomena as evidenced from the time-resolved fluorescence studies. Time-resolved spectroscopic investigations demonstrate the formation of the ground state of the reacting components (donor and acceptor) through recombination of triplet ion-pairs via formations of contact neutral radical produced by H-abstraction mechanism.     

A Voltage-Responsive Synthetic Cl−-Channel Regulated by pH

Transmembrane protein channels are an important inspiration for the design of artificial ion channels. Their dipolar structure helps overcome the high energy barrier to selectively translocate water and ions sharing one pathway, across the cell membrane. Herein, we report that the amino-imidazole (Imu) amphiphiles self-assemble via multiple H-bonding to form stable artificial Cl⁻-channels within lipid bilayers. The alignment of water/Cl⁻ wires influences the conduction of ions, envisioned to diffuse along the hydrophilic pathways; at acidic pH, Cl⁻/H⁺ symport conducts along a partly protonated channel, while at basic pH, higher Cl⁻/OH⁻ antiport translocate through a neutral channel configuration, which can be greatly activated by applying strong electric field. This voltage/pH regulated channel system represents an unexplored alternative for ion-pumping along artificial ion-channels, parallel to that of biology.     

Products of hydrolysis of (ferrocenylmethyl)trimethylammonium iodide: Synthesis of hydroxymethylferrocene and bis(ferrocenylmethyl) ether

The attempted coupling of (ferrocenylmethyl)trimethylammonium iodide (1) with 1,4,7-(triformyl)-1,4,7,10-tetraazacyclododecane (2) in water led to the formation of the expected compound 1-(ferrocenemethyl)-4,7,10-(triformyl)-1,4,7,10-tetraazacyclododecane (3). In addition, hydrolysis of the ferrocenyl precursor 1 led to the formation of two other known compounds, hydroxymethylferrocene (4) and bis(ferrocenylmethyl) ether (5). An X-ray crystal structure determination of 4 revealed the presence of H-bonding between the hydroxyl groups of one molecule of 4 and the oxygen atom of an adjacent molecule resulting in a left-handed helical chain of molecules lying along the b-axis direction. The O?O distances are significantly shorter than those found in previously reported structures of hydroxymethylferrocene derivatives indicative of moderate strength H-bonding interactions. In the structure of 5, the orientation of the ferrocenyl groups are staggered relative to a vector comprising the two carbons of the C-O-C linker.     

纳米水滴及真空中β-环糊精和对-甲基苯酚1:1包结物的约束动力学模拟研究

Two systems of 1: 1 inclusion of host β-cyclodextrin and guest p-cresol in nano-drip including 427 H2O molecules and in vacuum have been studied by the constrain molecular dynamics simulation technique with pcff force field and Rattle bond algorithm. The analysis on the dynamic structure of inclusion and radial distribution function of several kinds of oxygen atoms shows that the CD inclusion was stable during the simulation time period in two systems and none of water molecule was found to move into the CD cavity in the drip within 200 ps which conformed the hydrophobic property of CD cavity. In the drip,an obvious hydration caused by H-bonding existing in the CD hydrophilic outsides was observed,and it agreed well with the CD properties. The obvious H-bonding interactions existing between phenyl hydroxyl and water molecules in the drip and between phenyl hydroxyl and CD cavity in vacuum made the guest molecule insert into the CD cavity shallower in drip case than in vacuum case. It was concluded that the constrain molecular dynamics simulation technique can be used to investigate the dynamic behavior of CD aqueous solution.     

Multifunctional polyesters as new candidate materials for biomedical applications. Synthesis and structural characterization

The present work was aimed at the development of functional polymeric materials to be used in the targeted delivery of proteic drug and tissue engineering fields. The adopted strategy was based on the design of special polymer classes whose structures and functionality could be easily modified by finely tuned synthetic procedures. Poly(ether ester)s containing H-bonding units were chosen as promising materials for the proposed applications. Commercially available precursors were successfully used for the synthesis of symmetrical diesters containing different H-bonding groups (amide, carbamate, and urea moieties). In all cases, pure products were obtained in good yields. Bulk polycondensation of the monomeric precursors with different mixtures of 1,4-butanediol and PEG 1000 diol afforded a variety of high molecular weight polymeric structures. Physical-chemical characterization of the polymers indicates that their thermal, mechanical, and swelling properties can be tailored by a proper selection of the H-bonding group and of the composition of the feed mixture.     

二维衰减全反射红外光谱研究水在聚酰亚胺/二氧化硅纳米高分子复合膜中的吸附扩散行为

考虑到基于聚酰亚胺衍生物的电子器件的稳定性和性能,运用二维衰减全反射红外相关光潜研究了水在聚酰亚胺衍生物:poly(4’4- oxydiphenylene pyromellitimide)和二氧化硅的纳米高分子复合膜中的动态吸附和扩散行为．二维相关光谱区分出了三种不同氢键强度的水分子状态,同时,氢键的数量和强度还对不同状态水分子的扩散速率起了决定性的作用,和PI聚合物本身以及PI表面残留的硅酸形成氢键的水分子的扩散速度则最慢.     

Syntheses and Crystal Structures of Two Ion Pair Complexes, [Ru(bpy)3]2[Fe(CN)6]I · 7H2O and [Ru(bpy)3]- [Fe(CN)5NO]CH3OH · H2O

Two ion pair complexes, [Ru(bpy)₃]₂[Fe(CN)₆]I [sdot] 7H₃O (1) and [Ru(bpy)₃][Fe(CN)₅NO](CH₃OH) [sdot] H₂O (2) (bpy = 2,2-bipyridine) have been synthesized and structurally characterized. X-Ray crystallographic structures of 1 and 2 both show Fe(III) and Ru(II) in distorted octahedral environments. In both complexes, H-bonding interactions between an uncoordinated water molecule and the nitrogen atom of a cyano group exist.     

Zinc(II) and cadmium(II) complexes of Schiff bases derived from amino acids and pyridine-3-carboxaldehyde: synthesis,crystal structures,and fluorescence

Two d¹⁰ Schiff-base complexes, Zn₂(L₁)₂(H₂O)₆ ? SO₄ (1) and Cd(L₂)₂(H₂O)₄ (2) [HL₁ = 3-((pyrid-3-yl)-methylene)aminobenzoic acid; HL₂ = 4-((pyrid-3-yl)-methylene)aminobenzoic acid], have been synthesized and structurally characterized by elemental analyses, FT-IR spectra, and thermal studies, as well as single crystal X-ray diffraction. Complex 1 is a dinuclear macrocyclic structure with 22-membered rings and is assembled into a 3-D sandwich supramolecular network motif through H-bonding interactions; 2 is a mononuclear structure and is interlinked through H-bonding and π ··· π stacking contacts to generate another 3-D supramolecular network. Furthermore, fluorescent properties of the two complexes are also reported.     

Space Group Distribution in Substituted Phenols

1INTRODUCTIONThedesignofmolecularcrystalmaterialsisoneoftheveryactiveresearchareastoday"-".Itsfirststepisthedesignofmoleculewithdesiredproperties.Thesecondstepinvo1vesinpackingthemoleculesintoalatticestructureinadesirablemanner.Tocontrolmolecularpacking,scientistsshouldknowtherulesgoverningtheprocessthatmoleculesassemblethemselvesintothree-dimensionalcrystalstructureorotherorderedmediawithlowerdimensionalitysuchasliquidcrystalormonolayerstruc-:ture,amongotherthings.lnmolecularcrystals,mol…