Solvent-dependent 44 square grid and 64.82 NbO frameworks formed by Cu(Pyac)2 (bis3-(4-pyridyl)pentane-2,4-dionatocopper(ii))Electronic supplementary information (ESI) available: microanalyses of 1, 2, 6 and 10. See http://www.rsc.org/suppdata/cc/b3/b305457h/ | Synapse