Synthesis, structural characterization, antibiotics sensing and coordination chemistry of a fluorescent 4-amino-1,8-naphthalimide Tröger’s base supramolecular scaffold
June I. Lovitt, Deivasigamani Umadevi, P. Raja Lakshmi, Brendan Twamley, Thorfinnur Gunnlaugsson, Sankarasekaran Shanmugaraju
Abstract
The solvothermal synthesis and structural characterization of two new supramolecular coordination polymers featuring a unique V-shaped ligand bis-[N-(3-pyridyl)methyl)]-9,18-methano-1,8-naphthalimide-[b,f][1,5]diazocine (TBNap), are reported. The ligand TBNap was synthesized as a racemic mixture and the molecular structure was analyzed crystallographically. TBNap showed a positive solvatochromism effect which was further supported by DFT calculations illustrating the D-π-A type fluorophore effects within the ligand structures. TBNap was further employed as a potential fluorescence probe for the discriminative sensing of structurally assorted antibiotics. A strong fluorescence quenching and preferential binding affinity were realized for nitro-containing antibiotics, i.e., Furazolidone, Nitrofurantoin and Nitrofurazone. The solvothermal reaction of TBNap with Cd(OAc)2‧2H2O afforded a one-dimensional coordination polymer (TB-CP-1, poly-[Cd(TBNap)(OAc)2]). Similarly, reaction between TBNap and CdCl2.4H2O in DMF-C2H5OH rendered a 4,4’-2D coordination sheet (TB-CP-2, poly-[CdCl2(TBNap)]·DMF). The extended polymeric structures are further propagated into 3D supramolecular network through multiple face-to-face π-π interaction.