Synthesis and Structures of Metallated N‐Heterocyclic Derivatives

The synthesis and structures of five new compounds are reported. [Mg(6‐Oq)₂(phen)₂] ( 1 ), [Na(phen)₃][(6‐HOq)(6‐Oq)] ( 2 ), 1/∞[Cu(3‐Opy)(3‐HOpy)₂(PPh₃)]_∞ ( 3 ), 1/∞[Cu₂{μ‐(6‐Oq)}(PPh₃)₂]_∞ ( 4 ) and [Cu₂(pht)₂(μ‐dppm)₂] ( 5 ) (6‐HOq = 6‐hydroxyquinoline; phen = 1,10‐phenanthroline, 3‐HOpy = 3‐hydroxypyridine; Hpht = phthalimide; dppm = bis‐(diphenylphosphino)methane) were prepared by deprotonation of N‐heterocyclic aromatic compounds with metal alkoxides. 1 – 5 represent useful starting materials for investigating the supramolecular cordination chemistry of organic anhydrides.     

Rapid Prediction of the Hydrogen Bond Cooperativity in N‐methylacetamide Chains

A method is proposed to rapidly predict the hydrogen bond cooperativity in N‐methylacetamide chains. The parameters needed are obtained from the fittings to the hydrogen bonding energies in the formamide chains containing 2 to 8 monomeric units. The scheme is then used to calculate the individual hydrogen bonding energies in N‐methylacetamide chains containing 2 to 7 monomeric units. The cooperativity predicted is in good agreement with those obtained from MP2/6‐31+G** calculations by including the BSSE correction. Our scheme is further employed to predict the individual hydrogen bonding energies in larger N‐methylacetamide chains containing up to 200 monomeric N‐methylacetamide units, to which the MP2 method cannot be applied. Based on our scheme, a cooperative effect of over 170 % of the dimer hydrogen bonding energy in long N‐methylacetamide chains is predicted. The method is also applied to heterogeneous chains containing formamide, acetamide, N‐methylformamide, and N‐methylacetamide. The individual hydrogen bonding energies in these heterogeneous chains are also in good agreement with those obtained from MP2 calculations with the BSSE correction, further demonstrating that our method is reasonable.     

Hydrogen Bond Cooperativity and the Three‐Dimensional Structures of Water Nonamers and Decamers

Broadband rotational spectroscopy of water clusters produced in a pulsed molecular jet expansion has been used to determine the oxygen atom geometry in three isomers of the nonamer and two isomers of the decamer. The isomers for each cluster size have the same nominal geometry but differ in the arrangement of their hydrogen bond networks. The nearest neighbor O? O distances show a characteristic pattern for each hydrogen bond network isomer that is caused by three‐body effects that produce cooperative hydrogen bonding. The observed structures are the lowest energy cluster geometries identified by quantum chemistry and the experimental and theoretical O? O distances are in good agreement. The cooperativity effects revealed by the hydrogen bond O? O distance variations are shown to be consistent with a simple model for hydrogen bonding in water that takes into account the cooperative and anticooperative bonding effects of nearby water molecules.     

Influence of Rubidium Cations on Hydrogen and Deuterium Electrosorption in Palladium.

Abstract

A comparative cyclic voltammetric study of the hydrogen and deuterium sorption into a thin layer palladium electrode has been performed in acidic and basic solution containing rubidium cations. As in the case of other alkali cations, rubidium appears to clearly influence the α - to β- phase transition only in basic solution.     

Hydrogen Bonds in Coal -The Influence of Coal Rank and the Recognition of a New Hydrogen Bond in Coal

By means of in-situ diffuse reflectance FTIR.The IR spectra of 6 coals with different ranks were obtained from room temperature to 230℃.A new curve fitting method was used to recognize the different hydrogen bonds in the coals.and the influence of coal ranks on the distribution of hydrogen bonds(HBs) in the coals and their thermal stability were discussed.The results show that there is another new HB(around 2514cm^-1) between the-SH in mercaptans or thiophenols and the nitrogen in the pyridine-like compounds in the coals.and the evidence for that was provided.The controversial band of the HB between hydroxyl and the nitrogen of the pyridine-like compounds was determined in the range of 3028-2984cm^-1,and the result is comsistent with but more specific than that of Painter et al.It was ound that the stability of different HBs in the coals is influenced by both coal rank and temperature,For some HBs.the higher the coal rank,the higher the stability of them.Within the temperature range of our research,the stability of the HB between the hydroxyl and the π bond increases to some extent for some coals at temperatures higher than 110 or 140℃.     

The Structures and Hydrogen Bonding Networks in Crystals of Alkylenediammonium Salts of Galactaric Acid

The crystal structures of five alkylenediammonium galactarates (1– 5) were determined because the information from these structures may provide some insight into the solid state structures of the poly(alkylene galactaramides) derived from these salts. In each case the meso-galactarate anion is in the extended conformation. In four out of the five cases associations between galactarate units led to alternating layers of anions and cations rather than the expected alternation of anion and cation found in ionic solids. All five salts display extensive hydrogen bonding involving ammonium and carboxylate groups and in some cases hydroxyl groups of the anion.     

Syntheses, Crystal Structures, and Conformations of 10,10-Spiro-Bilirubins

Summary. Crystal structure determinations of two novel bilirubin analogs with spirocyclohexyl and spirofluorenyl groups at C(10) are reported. Conformation-determining torsion angles and key hydrogen bond distances and angles are compared to those from molecular dynamics calculations, and to the corresponding data from X-ray determinations and molecular dynamics calculations of bilirubin. Like bilirubin, the component dipyrrinones of spirocyclohexyl and spirofluorenyl rubins are present in the bis-lactam form with (Z)-configuration double bonds at C(4) and C(15). Their crystal structures show considerable similarity to that of bilirubin: both pigments adopt a folded, intramolecularly hydrogen-bonded ridge-tile conformation stabilized by six hydrogen bonds. The interplanar angle of the spirocyclohexyl ridge-tile is nearly the same (94°) as that of bilirubin (95°), but the interplanar angle of the spirofluorenyl ridge-tile is noticeably smaller (84°). The hydrogen bond distances of both spiro-rubin crystal structures are generally longer by 0.1–0.2Å than those in bilirubin. Both new pigments exhibit excellent lipophilicity and, unlike bilirubin, are soluble in methanol.     

Evolution of Artificial Base Pairs with Hydrogen Bond Complementarity

Artificial base pairs,from the perspective of synthetic biology,are designed to contain the features of modularity,orthogonality,and manipulability.And the development of artificial base pairs has beat endowed with responsibility to understand the biological process,improve the recognition capacity and stability of aptamers,and develop the nucleoside drugs,diagnosis,and drag delivery.In this review,we first gave a concise introduction of artificial base pairs based on their interaction modes including alternative hydrogen bonding,hydrophobic interaction,and metal coordination.Then we displayed the detailed information of artificial base pairs with hydrogen bonding interaction,and analyzed how the changes of their structures affect their functions.Subsequently,we highlighted the applications of functional artificial base pairs in aptamer discovery,diagnosis,and drug delivery.Finally,an insight into the remaining challenges and future perspective of the artificial bases was provided.     

Indole‐N‐Carboxylic Acids and Indole‐N‐Carboxamides in Organic Synthesis

Indoles are ubiquitous structures that are found in natural products and biologically active molecules. The synthesis of indoles and indole‐involved synthetic methodologies in organic chemistry have been receiving considerable attention. Indole‐N‐carboxylic acids and derived indole‐N‐carboxamides are intriguing compounds, which have been widely used in organic synthesis, especially in multicomponent reactions and C?H functionalization of indoles. This Minireview summarizes the advances of reactions involving indole‐N‐carboxylic acids and indole‐N‐carboxamides in organic chemistry, and discusses the synthetic potential and perspective of this field.     

Syntheses,Crystal Structures and Luminescent Properties of Three Inorganic‐Organic Hybrid Frameworks Constructed from 4,5‐Imidazoledicarboxylate

Three inorganic‐organic hybrid frameworks [Mn(HIMDC)(4,4′‐bipyo)_0.5(H₂O)]_n (1) , [Cd(H₂IMDC)₂(2,2′‐bipyo)] (2) and [Ca(HIMDC)(H₂O)₂·H₂O]_n (3) (H₃IMDC = 4,5‐imidazoledicarboxylate; 4,4′‐bipyo = 4,4′‐bipyridine‐N,N′‐dioxide; 2,2′‐bipyo= 2,2′‐bipyridine‐N,N′‐dioxide) have been hydrothermally synthesized and characterized by the elemental analyses, IR spectra, TG analysis and the single crystal diffraction. Both compounds 1 and 3 exhibit 2D layers while 2 is a monomer. It is noteworthy that compound 2 exhibits strong fluorescent emission in the solid state at room temperature.     

Excited‐State Hydrogen Bonding Strengthening and Weakening with Intramolecular Charge Transfer in Resorufin‐Water Complexes: A TD‐DFT Study

The geometric structures, infrared spectra and hydrogen bond binding energies of the various hydrogen‐bonded Res^?‐water complexes in states S0 and S1 have been calculated using the density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) methods, respectively. Based on the changes of the hydrogen bond lengths and binding energies as well as the spectral shifts of the vibrational mode of the hydroxyl groups, it is demonstrated that hydrogen bonds HB‐II, HB‐III and HB‐IV are strengthened while hydrogen bond HB‐I is weakened in the four singly hydrogen‐bonded Res^?‐Water complexes upon photoexcitation. When the four hydrogen bonds are formed simultaneously between one resorufin anion and four water molecules in the Res^?‐4Water complex, all the hydrogen bonds are weakened in both the ground and excited states compared with those in the corresponding singly hydrogen‐bonded Res^?‐Water complexes. Furthermore, in complex Res^?‐4Water, hydrogen bonds HB‐II and HB‐IV are strengthened while hydrogen bonds HB‐I and HB‐III are weakened after the electronic excitation. The hydrogen bond strengthening and weakening in the various hydrogen‐bonded Res^?‐water complexes should be due to the redistribution of the charges among the four heteroatoms (O_1‐3 and N₁) within the resorufin molecule upon the optical excitation.     

Computational Study of Hydrogen Bonding in Substituted Phenol‐Acetonitrile‐Water Clusters

The calculations for a water‐acetonitrile‐substituted phenols system and the comparison with the experimental parameters will be given. Here we study change in the nature of the interactions into the system with donor and acceptor electron substituents on the phenolic ring, the structures, relative energies and harmonic frequencies. The conformers showed a significant difference in the OH and CN band shift depending on the type of the hydrogen bond formed and the position of the substituent on the phenolic ring. The cyclical hydrogen bonds between water‐acetonitrile and substituted phenol OH are important evidence of the relative stability in the system under study.     

稀土与N-对甲苯磺酰甘氨酸配合物的合成、晶体结构与性质

Complexes { [Ln（H20）2（TsGlyH）a]m·nH2O}∞ （Ln=La （1）, m=2, n=6; Nd （2）, m=2, n=7; Eu （3）, m=2, n= 0; Gd （4）, m=2, n=2; Er （5）, m=3, n=5 and Yb （6）, m=3, n=0, TsGlyH=N-p-tosylglycine monoanion）, have been prepared and characterized by IR spectra, elemental analysis, and TG-DTG 4 and 5 were structurally determined by X-ray diffraction analysis, showing that both of them are comprised of a one dimensional chain structure established via the coordination of μ-carboxylate groups from N-p-tosylglycinate to the corresponding lanthanide（Ⅲ） ions. The one dimensional chains were found inclined to form two-dimensional network via hydrogen bonding and then three dimensional network structure via non-classical hydrogen bonding. The fluorescence spectra of them revealed that the fluorescence of the ligand was quenched by Ln（Ⅲ） ions. In the tested biological activity experiments, they behaved inhibiting effects against the growth of bacteria, indicating that it is a potential medicament worthy of further investigation.     

Antimony(V) Bromide and Polybromide Complexes with N‐alkylated Quinolinium or Isoquinolinium Cations: Substituent‐dependent Assembly of Polymeric Frameworks

Reactions of [Sb^IIIBr₆]^3– with Br₂ in HBr in the presence of N‐substituted quinolinium or isoquinolinium cations result in new complexes of hexabromidoantimonates of Sb^V and their polybromide adducts: (N‐MeQuin)₂{[SbBr₆](Br₃)} ( 1 ), (N‐MeIsoquin)₂{[SbBr₆](Br₃)} ( 2 ), and (N‐EtQuin)[SbBr₆] ( 3 ). Thermal stability was studied; estimated energies of supramolecular Br ··· Br interactions were calculated.     

Two Modifications of NH4HPO3F: Synthesis and Crystal Structure

The α and β modifications of NH₄HPO₃F were synthesized and characterized with single crystal X‐ray diffraction. The crystal structure of α‐NH₄HPO₃F determined at 180 K is monoclinic, space group P2₁/n, with a = 7.4650(1), b = 15.586(2), c = 7.5785(9) Å, β = 108.769(9)°, V = 834.9(2) ų, Z = 8, and R₁ = 0.0376 and wR₂ = 0.0818. β‐NH₄HPO₃F measured at 310 K crystallizes in the triclinic space group, P 1, with a = 7.481(1), b = 7.511(1), c = 7.782(1) Å, α = 84.31(1), β = 84.20(1), γ = 68.67(2)°, V = 404.31(9) ų, Z = 4, and R₁ = 0.0254 and wR₂ = 0.0735. A phase transition was not observed between 180 and 310 K for β‐NH₄HPO₃F. Both modifications of NH₄HPO₄F consist of HPO₃F^– and NH₄⁺ units. Two pairs of two unique anions are linked to each other by O–H…O hydrogen bonds to form cyclic tetramers held together by N–H…O bonds. No O–H…F or N–H…F bonds were observed.     

Palladium‐Catalyzed Carbon–Fluorine and Carbon–Hydrogen Bond Alumination of Fluoroarenes and Heteroarenes

Through serendipitous discovery, a palladium bis(phosphine) complex was identified as a catalyst for the selective transformation of sp²C−F and sp²C−H bonds of fluoroarenes and heteroarenes to sp²C−Al bonds (19 examples, 1 mol % Pd loading). The carbon–fluorine bond functionalization reaction is highly selective for the formation of organoaluminium products in preference to hydrodefluorination products (selectivity=4.4:1 to 27:1). Evidence is presented for a tandem catalytic process in which hydrodefluorination is followed by sp²C−H alumination.