Ramesh K. Metre

Multi-pyrene assemblies supported on stannoxane frameworks: synthesis, structure and photophysical studies.

Organostannoxanes have been used as scaffolds for the preparation of multi-chromophore assemblies. A single-step synthesis procedure allows the preparation of compounds in which the number of chromophore units can be varied from two to six. Thus, the reactions of pyrene sulfonic acid (PySO3H) or C16H9CHNC6H3(COOH)2(LH2) with various organotin precursors gave pyrene-containing organostannoxanes, that is, [Ph3 SnPySO3]6 (1), [{(Me2Sn)2(μ3-O)(μ-OH)PySO3}2{(Me2Sn)2(μ3-O)(μ-OH)H2O}2⋅2 PySO3] (2), [{tBu2Sn(OH)PySO3}2] (3), [{(nBuSn)12(O)14(OH)6{PySO3}2] (4), and [{(nBu2Sn)L}3]2⋅C6H5CH3 (5). Compounds 1-5 were characterized by using X-ray crystallography. Compounds 1 and 5 are 24-membered macrocycles. Macrocycle 1 possesses intramolecular π-π stacking interactions. An unusual co-crystal of two tetrameric ladders in 2 was observed in which one of the components of the co-crystal is neutral whereas the other is dicationic and two pyrenesulfonate counterions are present to balance the overall charge. In the solid state these compounds reveal rich supramolecular structures. Photophysical studies on 1-5 reveal that interactions in the solid state lead to considerable broadening of the emission bands.

Isomorphic Co(II) and Zn(II) phosphonates: co-crystal formation of [{M2(η1-DMPzH)4(Cl3CPO3)2}{M(η1-DMPzH)2Cl2}2](toluene)2 (M = Co(II) and Zn(II))

Two pairs of isomorphic molecular phosphonates are reported. The first isomorphic pair involves the co-crystals [{Co2(η1-DMPzH)4(Cl3CPO3)2}{Co(η1-DMPzH)2Cl2}2](toluene)2 [1] and [{Zn2(η1-DMPzH)4(Cl3CPO3)2}{Zn(η1-DMPzH)2Cl2}2](toluene)2 [2] while the second isomorphic pair is {Co2(η1-DMPzH)2Cl2(Cl3CPO3)2}(HNEt3)2 [3] and {Zn2(η1-DMPzH)2Cl2(Cl3CPO3)2}(HNEt3)2 [4]. These have been prepared by multi-component reactions involving normal solution-state synthesis at room temperature. Change of reaction solvent from acetonitrile to methanol affords change of products from 1 and 2 to 3 and 4.

Bismuth Phosphinates: Temperature-Dependent Formation of a Macrocycle and 1D Coordination Polymer

GRAPHICAL ABSTRACT Abstract The reaction of Ph3Bi with a sterically hindered phosphinic acid, 1,1,2,3,3-pentamethyltrimethylene phosphinic acid, {cycP(O)OH·2H2O}, at two different temperatures, one at refluxing conditions and another at room temperature, in tetrahydrofuran has been investigated. At refluxing conditions, cleavage of two Bi-C bonds (of BiPh3) leads to the formation of a 16-member macrocycle [(PhBi)4(cycPO2)8] (1). On the other hand, the reaction at room temperature leads to the cleavage of one Bi-C bond only, affording a 1D polymer [(Ph2Bi)(cycPO2)]n, ((1,1,2,3,3-pentamethyltrimethylene phosphinate is denoted as cycPO2) (2). Both the complexes were characterized by single crystal X-ray diffraction. In both complexes the phosphinate ligands are present in an anisobidentate (bridging) coordination mode.