Synthesis,Crystal Structure and Theoretical Calculations of a Cadmium Complex Containing 3-Hydroxybenzoic Acid and 1,4-Bis(imidazol-1-yl)-butane

A new complex [Cd（hba）2（bib）]n·nH2O（1,Hhba = 3-hydroxybenzoic acid,bib = 1,4-bis（imidazol-1-yl）-butane） has been hydrothermally synthesized and characterized by elemental analysis,IR spectrum,thermogravimetric analysis,fluorescence spectrum,and singlecrystal X-ray diffraction.Yellow crystal crystallizes in the orthorhombic system,space group Pbca with a = 16.220（5）,b = 14.980（5）,c = 20.521（5） ？,V = 4986（3） ？~3,C（24）H（26）CdN4O7,Mr = 594.89,Dc = 1.585 g/cm^3,μ（Mo Kα） = 0.927 mm^（-1）,F（000） = 2416,Z = 8,the final R = 0.0242 and w R = 0.0589 for 4076 observed reflections（I 〉 2s（I））.In 1,the Cd（Ⅱ） ion takes a six-coordination mode,and bib ligand bridges adjacent Cd（Ⅱ） ions to generate 1D zigzag chains; these neighboring chains are connected by O–H···O hydrogen bonding interactions,producing a 2D folded layered structure.Furthermore,by O–H···O hydrogen bonding between layers and layers,a 3D supramolecular architecture is formed.In addition,we analyzed Natural Bond Orbital（NBO） in using the PBE0/LANL2 DZ method built in Gaussian 03 Program.The calculation results indicated obvious covalent interaction between the coordinated atoms and Cd（Ⅱ） ion.

Spectroscopic Characterizations of Metal-Complexes of 4-Hydroxybenzoic Acid With the Ni(Ⅱ),Mn(Ⅱ),and Cu(Ⅱ)Ions

One of the phenolic acids is 4-hydroxybenzoic acid(HBA)which takes the form of a white crystalline solid with a molecular formula of C 7H 6O 3,a melting point of 214.5℃and a molecular weight of 138.12 g·mol^(-1).It soluble in polar organic solvents like acetone and alcohols,and slightly soluble in chloroform and water.The reactions between the metal ions and the HBA were carried out under specific conditions like(molar reaction was 2∶2(ligand to metal),reaction temperature was 60℃,media was neutral(pH 7),and solvent was H 2O∶MeOH(1∶1).Under these conditions,the HBA was deprotonated to form(HOC_(6)H_(4)CO^(2);L^(-)).The ligand L-was coordinated to the metal ions forming the metal complexation.The reaction of 4-hydroxybenzoic acid(HOC 6H 4CO 2H;HL)with the Ni(Ⅱ),Mn(Ⅱ)and Cu(Ⅱ)ions afford metal-complexes with gross formula of[Ni_(2)L_(2)(NO_(3))_(2)(H_(2)O)_(4)],[Mn_(2)L_(2)(NO_(3))_(2)(H_(2)O)_(4)]and[Cu_(2)L_(2)(NO_(3))_(2)(H_(2)O)_(4)],respectively.These complexes were characterized by elemental analysis(CHN),magnetic susceptibility,UV-Vis spectra,infrared(IR),and X-ray powder diffraction(XRD)techniques.The complexes of HBA are insoluble in common solvents and hence molar conductance could not be measured,but this very insolubility indicates that the complexes are neutral.Data has demonstrated that the ligand(L^(-))was coordinated to the metal ion by bidentate bridging carboxylate group(COO^(-)),with an octahedral geometry.Thus,HBA is expected to act as bidentate uninegative ions and the coordination number of the metal ions is six.XRD results showed that the complexes possess uniform and organized microstructures in the nanometer range with a main diameter in the range of 11~28 nm.

Recent Advances in Microbial Degradation of 4-hydroxybenzoate-a Review

4-Hydroxybenzoate （4HBA） is a naturally occurring aromatic compound, as a key intermediate metabolite not only for natural products but also for arti- ficial products. There are four metabolic pathways for 4HBA： protocatechuate cleavage pathway; catechol cleavage pathway; anaerobic degradation pathway in anaerobes ; and gentisate cleavage pathway. The last pathway including a NIH shift reaction remains to be elucidated. In this review we emphasized on the NIH shift reaction involved in the 4HBA degrdation. The key enzymes of each 4HBA metabolic pathway also were introduced. Finnaly, we described the thermophilic Bacillus sp. B1 strain which was capable of degrading varous aromatic compounds including gHBA, and presented a direction for the research of NIH shift reaction.

POLYMER-SUPPORTED β-CYCLODEXTRIN CATALYST FOR SELECTIVE SYNTHESISOF 4-H YDROXYBENZOIC ACID

4-hydroxybenzoic acid was synthesized by one pot method using polymer-bonded β-aminopropionic acid-2-β-cyclodextrin as a catalyst.by which the selectivity for 4-hydroxybenzoic acid is 87%. A possible carboxylation mechanism in the presence of the title catalyst is discussed. Also.the recovery and reusage of the catalyst is studied.

A New Sesquiterpene-substituted Benzoic Acid from the Brown Alga Dictyopteris divaricata

A new sesquiterpene-substituted benzoic acid has been isolated from the brown Alga Dictyopteris divaricata Okam.. Its structure was elucidated as 3-[(2-hydroxy-2,5,5,8a-tetra- methyldecahydro-1-naphthalenyl)methyl]-4-hydroxybenzoic acid, named dictyvaric acid on the basis of spectroscopic methods including IR, HRFABMS, 1D and 2D NMR techniques.

How plants synthesize coenzyme Q

Coenzyme Q(CoQ)is a conserved redox-active lipid that has a wide distribution across the domains of life.CoQ plays a key role in the oxidative electron transfer chain and serves as a crucial antioxidant in cellular membranes.Our understanding of CoQ biosynthesis in eukaryotes has come mostly from studies of yeast.Recently,significant advances have been made in understanding CoQ biosynthesis in plants.Unique mitochondrial flavin-dependent monooxygenase and benzenoid ring precursor biosynthetic pathways have been discovered,providing new insights into the diversity of CoQ biosynthetic pathways and the evolution of phototrophic eukaryotes.We summarize research progress on CoQ biosynthesis and regulation in plants and recent efforts to increase the CoQ content in plant foods.