Spontaneous Self-Assembly of a 1,8-Naphthyridine into Diverse Crystalline 1D Nanostructures: Implications on the Stimuli-Responsive Luminescent Behaviour
The previously reported organic solid-state fluorophore 7-(3,4-dimethoxyphenyl)-2-ethoxy-4-phenyl-1,8-naphthyridine-3-carbonitrile 1 was found to spontaneously self-organize into diverse 1D crystalline nanostructures by choosing appropriate liquid phase self-assembly conditions. Experimental results, as well as DFT quantum calculations (at the M06-2X/6-31+G(d) level), shed light on the aggregation mechanism. This was found in good agreement with molecules being primarily joined together through intermolecular alignment caused by electrostatic interactions, as well as minimization of the steric repulsions. This alignment provokes the preferential growth of the crystalline materials into 1D a…
Polymorphism-Triggered Reversible Thermochromic Fluorescence of a simple 1,8-Naphthyridine
The fluorescent behavior in the solid state of a naphthyridine-based donor–acceptor heterocycle is presented. Synthesized as a crystalline blue-emissive solid (Pbca), the compound can easily be transformed in its P21/c polymorphic form by heating. The latter material shows blue to cyan emission switching triggered by a reversible thermally induced phase transformation. This fact, the reversible acidochromism, and the strong anisotropic fluorescence of the compound in the solid state, account for the potential of 1,8-naphthyridines as simple and highly tunable organic compounds in materials science.