Reaction of theophylline with [Rh-2(mu-OAc)(2)(mu-HNOCCF3)(2)] gave [Rh-2(mu-OAc)(2)(mu-HNOCCF3)(2) (theophylline)(2)]center dot 6H(2)O ( 1 ), whose crystal structure was determined by single-crystal X-ray diffraction. The dirhodium core, where the two different acetato and acetamidato ligands bridging the Rh-Rh bond are in a trans configuration, is occupied at either axial-side by two theophylline ligands through N(9) with the formation of two kinds of intra-molecular interligand C -H (theophylline)center dot center dot center dot O hydrogen bonds, one being a bifurcated hydrogen bond between the C(3)-methyl hydrogen as a donor and the acetato and amidato oxygens as acceptors and the other between the C(8) hydrogen and the acetato oxygen. In the crystal lattice, a discrete, hydrogen-bonding, cyclic hexameric water cluster with the flattened chair conformation is sandwiched between theophylline bases, providing the first water hexagon that intercalates between aromatic rings. The participation of the acetamidato NH group in the formation of a hydrogen bond with a water molecule belonging to the water hexagon that governs the crystal packing makes it impossible for the acetamidato ligand to form an intra-molecular hydrogen bond with O(6), causing the failure of the metal bonding to theophylline through N(7). A critical review on metal bonding properties of theophylline observed in so far reported crystal structures is given, emphasizing the significance of intra-molecular interligand interactions (H-bonding, electrostatic repulsion, and steric constraint) as a factor that could affect metal binding sites/modes of theophylline. (C) 2021 Published by Elsevier B.V.

An aqueous solution dissolving pyridoxal 5′-phosphate (PLP) was exposed to sun-light at room temperature to yield a photolysis product, 4b,9b-dihydro-4b,9b-dihydroxy-1,6-dimethyl-4,9-bis(phosphonooxymethyl){pyrido[3′,4′:2,3]furo[4,5-b]}pyrido[4,3-d]furan (1), whose structure was crystallographically determined. The product 1 was found to be a novel C(sp3)–C(sp3) side-sharing pyridodihydrofuran-condensed skeleton compound with the two pyridodihydrofuran planes taking a ‘V-shape’-like molecular configuration. Hydrogen bonding patterns of molecules of 1 in the crystal lattice are analyzed by the graph set approach. The most probable mechanism for the formation of 1 is described.

Structural information on the interaction between lead ion and its targeting biological substances is important not only for enriching coordination chemistry of lead but for successfully treating lead poisoning that is a present-day problem. This chapter provides structural data, mainly metal binding sites/modes, observed in crystal structures of lead complexes with biorelevant molecules, obtained from the Cambridge Structural Database (the CSD version 5.36 updated to May 2015) and the Protein Data Bank (PDB updated to February 2016). Ligands include (i) amino acids and small peptides, (ii) proteins, (iii) nucleic acid constituents, (iv) nucleic acids, (v) simple saccharides, and (vi) other biorelevant molecules involving lead-detoxification agents. For representative complexes of these ligands, some details on the environment of the metal coordination and structural characteristics are described.

This chapter provides structural data, mainly metal binding sites/modes, observed in crystal structures of alkali metal ion complexes containing low-molecular-weight ligands of biological relevance, mostly obtained from the Cambridge Structural Database (the CSD version 5.35 updated to February 2014). These ligands include (i) amino acids and small peptides, (ii) nucleic acid constituents (excluding quadruplexes and other oligonucleotides), (iii) simple carbohydrates, and (iv) naturally occurring antibiotic ionophores. For some representative complexes of these ligands, some details on the environment of the metal coordination and structural characteristics are described.

Three aluminum complexes supported by salen ligands derived from cis-1,2-cyclohexanediamine and salicylaldehyde derivatives were synthesized. They were characterized by 1H, 13C NMR spectra, and elemental analysis. X-ray diffraction analysis revealed that aluminum was in distorted square pyramidal geometry in 2. These complexes were employed as catalysts for the ring-opening polymerization (ROP) of L-lactide and rac-lactide. Complex 2 showed the highest activity among these complexes with isopropanol for the ROP of L-lactide and 3 showed the highest stereoselectivity for the ROP of rac-lactide attaining partially isotactic polylactide with a Pm of 0.75. The kinetic data of the polymerization utilizing 3 as catalyst showed that the polymeric rate was first order to the monomer and catalyst.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Treatment of cytosine with tris(2-aminoethyl)amine (tren) and Cu(ClO4)2·6H2O under alkaline conditions gave a ternary tren–Cu2+–cytosine complex, [{Cu(tren)}2(cytosinato)]·(ClO4)3·0.5H2O, whose crystal structure was determined by X-ray diffraction. In the structure of the [{Cu(tren)}2(cytosinato)]3+ cation, two tren-capped square-pyramidal Cu2+ ions bind to a cytosinate anion, one through the deprotonated N(1) of cytosine with the formation of an intra-molecular interligand hydrogen bond between the keto substituent O(2) of the base and the amino group of tren and the other through both the ring nitrogen N(3) and the exocyclic O(2) of the base, forming a four-membered chelate-ring. An overview on metal bonding properties of N(1)-unsubstituted cytosine observed in so far reported crystal structures is given, emphasizing the significance of intra-molecular interligand interaction as a factor that affects metal-binding sites of cytosine.

Titanium complexes bearing N,N-bidentate diamido derived from Schiff bases were investigated as catalysts for lactide polymerization.

Metal ions play a key role in nucleic acid structure and activity. The elucidation of factors/rules that govern the binding of metal ions is therefore an essential step for the better understanding of nucleic acid functions. In this review, we deal with stereospecific intra-molecular interligand interactions as such a factor, involving hydrogen-bonding, electrostatic interaction, and steric constraints, especially focusing on their significance as a factor that could affect base-specific metal bonding to adenine and guanine bases in the solid state. (C) 2013 Elsevier B.V. All rights reserved.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Ammonium bisdiethylphosphonate acrylate and methacrylate monomers were synthesized by an aza-Michael addition of 3-aminopropanol across the double bond of bisdiethylphosphonate, followed by acylation with (meth)acryloyl chloride. Free radical copolymerizations of the monomers with an acrylate-functional poly(ethylene oxide) (PEO) macromonomer produced graft copolymers. Quantitative deprotection of the alkylphosphonate groups, then adjustment of the pH to 7.74 ± 0.03, yielded graft copolymers with zwitterionic ammonium bisphosphonate backbones and PEO grafts. Copolymerization kinetic studies showed that the ammonium bisdiethylphosphonate methacrylate incorporated into the copolymers with PEO-acrylate well, but that the corresponding acrylate monomer reacted too slowly. The zwitterionic copolymers spontaneously assembled into aggregates in aqueous media.

Two hydrate pseudopolymorphs of 3-[(4-amino-2-methylpyrimidin-1-ium-5-yl)methyl]-4-methyl-1,3-thiazol-3-ium-5-yl hydrogen pyrophosphate (TPP), viz. a dihydrate, C12H18N4O7P2S·2H2O, (I), and a trihydrate, C12H18N4O7P2S·3H2O, (II), were obtained during a structural study of vitamin B1 coenzyme. In both compounds, TPP is a neutral zwitterion, with its pyrophosphate group doubly deprotonated and its pyrimidine ring protonated, and it assumes the usual `F' conformation in terms of the two torsion angles about the bonds by which the methylene group links the thiazolium and pyrimidinium rings [1.1 (3) and 79.7 (3)° for (I), and 2.0 (3) and 75.5 (3)° for (II)]. In (I), two TPP molecules are linked by a pair of O-H···O hydrogen bonds into a phosphate-pairing dimer. N-H···O hydrogen bonds connect the dimers into a sheet parallel to (101). In (II), the TPP molecules are self-assembled solely by N-H···O hydrogen bonds, generating a tape structure along [001]. A comparison of the four known hydrate pseudopolymorphs of TPP shows that the phosphate-pairing dimers are basic building units for the formation of two-dimensional networks.

Available data from clinical trials clearly demonstrate that cholesterol-lowering therapy with ezetimibe should be used after an adequate trial with statin medications has been attempted. However, because the use of ezetimibe is not regulated in Saskatchewan, it is not known if the patterns of prescribing typically follow accepted guidelines. We conducted a descriptive analysis of the use of ezetimibe with provincial health-administrative databases.

Four new metal–organic coordination polymers, [Cd2(sbpdc)2(bpy)] (1), [Cd(sbpdc)(bpp)1/2] (2), [Co(sbpdc)(bpy)] (3) and [Co(sbpdc)(bpp)(H2O)] (4) (H2sbpdc=sulfone-4,4′-biphenyldicarboxylic acid, bpy=4,4′-bipyridine, bpp=1,3-bis(4-pyridyl)propane) have been synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction, elemental analysis and IR spectra. Compound 1 displays a 3D 6-connected twofold interpenetrated net with pcu topology, while 2 contains 1D infinite Cd-O-Cd chains. Compound 3 is a new 3D binodal network with the point symbol of (63) (67⋅83), whereas compound 4 has a 1D double chain. Moreover, the PXRD, TGA, luminescent and magnetic property were also investigated.

Two new cadmium compounds [Cd3 (OH)2 (2,4-pydc)2] (1) and [Cd2(2,4-pydc)2(bpe)]·2H2O (2) (2,4-pydcH2=pyridine-2,4-dicarboxylic acid, bpe=1,2-bis(4-pyridyl)ethene) have been prepared under hydrothermal conditions at different pH values. The compounds were characterized by elemental analyses, IR spectra and thermogravimetric analyses and their structures were determined by single-crystal X-ray diffraction analysis. Compound 1 has a 3D framework constructed by 2D Cd-O(OH) layers and pillared 2,4-pydc ligands. Compound 2 also displays a 3D metal-organic framework with the Cd(II) centers connected by 2,4-pydc and bpe ligands. The differences in the structures indicate that the change of pH value has significant effects on the formation and structures of the final compounds. In addition, the luminescent properties of compounds 1–2 have also been studied.

In the title compound, {[Zn(2)(C(6)H(14)N(2)O(2))(2)(C(10)H(8)N(2))(3)](NO(3))(4)·0.6H(2)O·2C(3)H(7)NO}(n), the Zn(II) ion is six-coordinated with a distorted octa-hedral geometry by two carboxyl-ate O atoms and one amino N atom from two l-lysinate (l-lys) ligands, and three N atoms from three 4,4'-bipyridine (4,4'-bipy) ligands. The Zn(II) ions are connected by the carboxyl-ate groups of the l-lys ligands in the a-axis direction and the bridging 4,4'-bipy ligands in the b- and c-axis directions, forming a three-dimensional cationic framework with channels along [100]. The nitrate anions and solvent water and dimethyl-formamide (DMF) mol-ecules are located in the channels and linked to the cationic framework by N-H⋯O and O-H⋯O hydrogen bonds. The occupancy of the water mol-ecule was fixed at 0.6. One of the DMF mol-ecules is disordered over two sets of sites, with an occupancy ratio of 0.632:0.368 (11).

The asymmetric unit of the title polymeric complex, [Cd-2(C13H7NO4)(OH)(2)] n, consists of two independent Cd II atoms, one 5-(4-carboxyphenyl) pyridine-2-carboxylate ligand and two hydroxy groups. One Cd-II atom is six-coordinated by two O atoms from two ligand molecules and by four mu(3)-OH groups in a distorted trigonal-prismatic geometry. The other is five-coordinated by one N and two O atoms from two ligands and by two mu(3)-OH groups, forming a distorted squarepyramidal geometry. The two independent Cd-II atoms are connected by the ligand molecules and the OH groups into a three-dimensional framework. O-H center dot center dot center dot O hydrogen bonds between the OH groups and the carboxylate O atoms are observed.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.