Role of 4,4′-bipyridine versus longer spacers 4,4′-azobipyridine, 1,2-bis(4-pyridyl)ethylene, and 1,2-bis(pyridin-3-ylmethylene)hydrazine in the formation of thermally labile metallophosphate coordination polymersElectronic supplementary information (ESI) available: Selected bond lengths and angles in tables and figures for 1-5 and 9-11. CCDC 942679-942683 and 1015310-1015312. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4qi00149d

One dimensional metallophosphate coordination polymers {[M(dtbp) 2 (azopy)(H 2 O) 2 ]·(azopy)} x (M = Mn ( 1 ); Co ( 2 ); Cu ( 3 ); Cd ( 4 )) have been synthesized from the reaction of a suitable metal precursor with di- tert -butylphosphate (dtbp-H) in the presence of ditopic linker 4,4′-azobipyridine (azopy) in a 1 : 2 : 2 stoichiometric ratio. Isostructural compounds 1-4 have been characterized by analytical and spectroscopic methods and single crystal X-ray diffraction studies. Single crystal X-ray diffraction measurements further reveal that compounds 1-3 (all C 2/ c ) and 4 ( P 1&cmb.macr;) are linear 1D coordination polymers. The uncoordinated 4,4′-azobipyridine in the lattice is responsible for the conversion of these 1D coordination polymers into 3D supramolecular assemblies through O-H N hydrogen bonding interactions between coordinated water and N-centers of an azopy ligand. Similar reactions carried out using 1,2-bis(4-pyridyl)ethylene (bpe) as the linker yielded compounds having the formula {[M(dtbp) 2 (bpe)(H 2 O) 2 ]·(bpe)} x (M = Mn ( 5 ); Co ( 6 ); Cu ( 7 ); Ni ( 8 )). Compounds 5-8 have been characterized by analytical and spectroscopic methods. Preliminary single crystal X-ray diffraction studies carried out on poorly diffracting crystals of 5 and 6 establish their isostructural nature to 1-4 , also displaying a similar supramolecular aggregation behaviour. A longer ditopic N , N ′-donor ligand, 1,2-bis(pyridin-3-ylmethylene)hydrazine (bph), has been used in place of bpe/azoby to synthesize 1-dimensional coordination polymers [{M(bph)(H 2 O) 4 }{(dtbp) 2 }] (M = Ni ( 9 ) and M = Co ( 10 )) and [Cd(bph) 3 (dtbp) 2 ] n ( 11 ) which have completely different structural motifs when compared to 1-4 . Uncoordinated N-donors spacers in the title compounds facilitate interesting orthogonal H-bonding, leading to the formation of 3-D polymeric networks.