Gundog Yucesan

Structural consequences of the steric effects of the organoimine ligand in the oxovanadium–organophosphonate/copper–mephenterpy family of hybrid oxides (mephenterpy = 4′-(4-methyphenyl)-2,2′∶6′,2″-terpyridine)

Hydrothermal reactions of CuSO4·5H2O, Na3VO4, 4′-(4-methylphenyl)-2,2′∶6′,2″-terpyridine (mephenterpy) and the appropriate diphosphonic acid provided a series of materials of the Cu(II)–mephenterpy/oxovanadium organophosphonate family. Four one-dimensional compounds were isolated: [{Cu(mephenterpy)}(VO2)(HO3PCH2PO3)] (1), [{Cu(mephenterpy)}2(V3O6)(O3PCH2CH2PO3)(HO3PCH2CH2PO3)] (2), [{Cu(mephenterpy)}(VO2)(HO3PCH2CH2CH2PO3)] (3) and [{Cu(mephenterpy)}2(V2O5)2(O3PCH2CH2CH2PO3)] (4). Although all share a common dimensionality, the detailed connectivities within the chains result in four distinct vanadophosphonate substructures: {(VO2)(HO3PCH2CH2PO3)}2n−n chains in 1, {(V3O6)(O3PCH2CH2PO3)(HO3PCH2CH2PO3)}4n−n chains in 2, [(VO2)2{HO3P(CH2)3PO3}2]4− rings in 3 and [(V2O5)2{O3P(CH2)3PO3}]4n−n chains in 4. When the diphosphonate tether is a butylene group, the copper phase [Cu(mephenterpy){HO3P(CH2)4PO3H}]·H2O (5) is isolated.

Secondary metal–ligand cationic subunits {ML}n+ as structural determinants in the oxovanadium/phenylphosphonate/{ML}n+ system, where {ML} is a Cu2+/organonitrogen moiety

The hydrothermal reactions of CuSO4·5H2O, Na3VO4, phenylphosphonic acid and the appropriate organonitrogen ligand yield a series of materials of the oxovanadium/phenylphosphonate/Cu(II)–ligand family. The structural influences of the organonitrogen ligand are most pronounced in the dimensionality of the material. Thus, [{Cu(phen)}VO(O3PC6H5)2]·0.5 H2O (1) is one-dimensional; [{Cu2(bpytrz)(H2O)}VO(O3PC6H5)2(HO3PC6H5)] (2) (bpytrz = 3,5-di-2-pyridyl-1,2,4-triazolate) is two-dimensional, and [{Cu(4,4′-bpy)}0.5VO2(O3PC6H5)] (3) is three-dimensional. When the phenylphosphonate component is replaced by phenyl-1,2-diphosphonate, the three-dimensional material [{Cu(4,4′-bpy)}VO2(HO3PC6H4PO3)] (4) is obtained. In contrast to the structure of 3 which exhibits a three-dimensional Cu–V–P–O substructure which encapsulates the {Cu2(bpy)}4+ unit, 4 exhibits the more common “pillared” layer structure with Cu–V–P–O networks buttressed by the 4,4′-bipyridyl groups. When the starting materials that gave 4 are reacted at 200 °C rather than 120 °C, the copper phase [{Cu(4,4′-bpy)0.5}{Cu(H2O)}(O3PC6H4PO3)]·H2O (5) is obtained. Compound 5 exhibits a “pillared” layer structure with a Cu–P–O network exhibiting embedded binuclear copper(II) sites.

Influence of alkyl chain length on the surface activity of antibacterial polymers derived from ROMP

The purpose of this study is to understand the antibacterial properties of cationic polymers on solid surfaces by investigating the structure-activity relationships. The polymer synthesis was carried via ring opening metathesis polymerization (ROMP) of oxanorbornene derivatives. Modulation of molecular weights and alkyl chain lengths of the polymers were studied to investigate the antibacterial properties on the glass surface. Fluorescein (Na salt) staining contact angle measurements were used to characterize the positive charge density and hydrophobicity on the polymer coated surfaces. Positive charge density for the surface coated polymers with molecular weights of 3000 and 10,000 g mol(-1) is observed to be in the range of 2.3-28.5 nmol cm(-2). The ROMP based cationic pyridinium polymer with hexyl unit exhibited the highest bactericidal efficiency against Escherichia coli on solid surface killing 99% of the bacteria in 5 min. However, phenyl and octyl functionalized quaternary pyridinium groups exhibited lower biocidal properties on the solid surfaces compared to their solution phase biocidal properties. Studying the effect of threshold polymer concentrations on the antibacterial properties indicated that changing the concentrations of polymer coatings on the solid surface dramatically influences antibacterial efficiency.

Mimicking cellular phospholipid bilayer packing creates predictable crystalline molecular metal–organophosphonate macrocycles and cages

We report a novel mechanism to create a predictable molecular metal–organophosphonate cage [Zn2(2,2′-bpy)2(H2ODP)2(H4ODP)]·2H2O (1·2H2O) (H4ODP = 1,8-octanediphosphonic acid) and a macrocycle [Cu2(2,2′-bpy)2(H2-1,4-NDPA)2(H2O)2]·H2O (2) (H4-1,4-NDPA = 1,4-naphthalene diphosphonic acid). The structures were solved using single crystal X-ray diffraction. The photoluminescence properties of 1·2H2O, investigated both in solution and in the solid-state at room temperature, indicated that the tighter zinc binding in the solid state leads to the augmentation of fluorescence. The ORCA molecular structure optimization calculations for 1·2H2O suggest a slight opening of the cage structure in non-polar solvents while in polar solvents the cage is tightened. Toxicity analysis with Caco-2 cells indicates that the molecule is readily tolerated by intestinal cells.