Luminescent cadmium 5-sulfoisophthalate dipyridylpiperazine coordination polymers with ladder, interpenetrated binodal net, or nanotube-embedded layer topologies

Abstract The conformationally flexible dipyridyl ligands bis(3-pyridylmethyl)piperazine (3-bpmp), bis(4-pyridylmethyl)piperazine (4-bpmp) and bis(4-pyridylmethyl)homopiperazine (4-bpmh) have been utilized to prepare the cadmium 5-sulfoisophthalate (sip) coordination polymers {[Cd 2 (sip) 2 (3-bpmpH 2 )(H 2 O) 4 ]·19H 2 O} n ( 1 ), {[Cd 2 (sip) 2 (4-bpmpH 2 )(4-bpmp)]·4H 2 O} n ( 2 ), and {[Cd(sip)(4-bpmhH)]·11H 2 O} n ( 3 ). Compound 1 possesses 1D ladder motifs with parallel [Cd(sip)] n n − chains strutted by doubly protonated 3-bpmpH 2 2+ rungs. [Cd(sip)] n n − ribbons with bound sip sulfonate groups are present in both 2 and 3 , but different geometric dispositions of the pyridyl arms of the tethering ligands effect a variance in dimensionality. The “linear” 4-bpmpH ligands in 2 link [Cd(sip)] n n − ribbons into a 3-fold interpenetrated 3,5-connected binodal 3D lattice with (4 2 6)(4 2 6 5 8 3 ) topology. In contrast, pairs of curled 4-bpmhH ligands in 3 connect [Cd(sip)] n n − ribbons into a unique 2,3,5-trinodal looped network with (4)(4 2 6)(4 3 6.8 4 10 2 ) topology. The ligand-pair loops bracket water-filled one-dimensional (1-D) elliptical nanotubules. All materials exhibited blue or violet emission upon irradiation with ultraviolet light.