The hydrothermal reaction of an aqueous ammonium heptamolybdate solution with first-row transition metal salts in the presence of 2-aminopyridine at around 180°C and under autogenous pressure yields several molybdates, such as the 1D chains in (C 5 N 2 H 7 ) 4 (3)] The structures of these materials were established by single-crystal and powder X-ray diffraction
The hydrothermal reaction of an aqueous ammonium heptamolybdate solution with cobalt or copper metal salts in the presence of imidazole (imi) or pyrazole (pz) in the temperature range 120-180°C and at autogenous pressure yields four fully oxidized metal-complex-templated octamolybdates, namely [
The anion binding properties of bile acid-based cyclic bisbenzimidazolium receptors 6-8 bridged with m-xylene, p-xylene, and 2,6-dimethylpyridine have been studied. Receptors 6 and 7 exhibit much higher binding affinity for fluoride and chloride ions, respectively, as compared to the imidazolium receptors 1 and 2. Receptor 8, however, shows high selectivity but very low binding affinity for anions due to the presence of pyridyl nitrogen. The single-crystal X-ray structure of imidazolium receptor 10-(Br)2 containing pyridyl spacer reveals the binding pattern.
The synthesis of four new Anderson-Evans type cluster based solids was carried out from an aqueous solution containing sodium molybdate, chromium chloride, cupric chloride and pyrazole at room temperature: [{Cr 3 O(CH 3 COO) 6 (H 2 O) 3 } 2 {H 7 CrMo 6 O 24 }]Á24H 2 O, 1; [{Cu 2 (ox)(pz) 4 }{H 7 CrMo 6 O 24 }]Á11H 2 O, 3; [{Cu(pz) 2 (H 2 O) 2 }{Cu 2 (ox)(pz) 4 }{H 5 CrMo 6 O 24 }]Á 8H 2 O, 4; and [{Cu(pz) 3 Cl}{Cu 2 (ox)(pz) 4 }{H 6 CrMo 6 O 24 }]Á8H 2 O, 5.In 1, the discrete Anderson-Evans cluster aggregates with trimeric chromium acetate cationic complex through supramolecular interactions. In 3-5, the Anderson-Evans cluster is covalently linked into a 1D chain through oxalate bridged copper pyrazole units. In 3, the chains are further stabilized by water oligomers. In 4 and 5, the chains are covalently linked into 2D sheets by different copper pyrazole complexes. The oxalate molecules in 3-5 are probably generated in situ in the reaction medium, through a reductive coupling of dissolved carbon dioxide assisted by copper pyrazole units.
Two new fully oxidized polyoxovanadate cluster-based solids (C 4 N 2 S 2 H 14) 2 [H 2 V 10 O 28 ]⋅4H 2 O, 1 and (C 4 N 2 S 2 H 14) 5 [H 4 V 15 O 42 ] 2 ⋅10H 2 O, 2 are crystallized under self-assembly process in the presence of cysteamine. In both 1 and 2, cysteamines are oxidized forming disulphide linkages and occur as counter cations. The organic cations assemble around V 10 O 28 cluster anions in 1 whereas they aggregate around V 15 O 42 clusters in 2. pH appears to be the structure determinant in the occurrence of decavanadate cluster in 1 and pentadecavanadate in 2, with the same counter cation.
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