Synthesis, structural characterization, antibiotics sensing and coordination chemistry of a fluorescent 4-amino-1,8-naphthalimide Troger's base supramolecular scaffold

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-pi-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)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)]center dot DMF). The extended polymeric structures are further propagated into 3D supramolecular network through multiple face-to-face pi-pi interaction.

Automated summary

The study reports the solvothermal synthesis and structural characterization of two new supramolecular coordination polymers using a unique V-shaped ligand TBNap. The ligand exhibits positive solvatochromism effect in different solvents and can be used as a fluorescence probe for discriminative sensing of structurally assorted antibiotics.