Fundamental research studies in the field of phenothiazine derivatives
Phenothiazine derivatives have a long history behind, with consecutive periods of scientific concern which generated top compounds in major areas of applied chemistry, specifically dyes, pharmaceuticals, pesticides, additives for lubricants and polymers. In current research the scientific apprehension switched towards new derivatives with tailored electro-optic properties suitable for detailed materials science investigations.
Our research group deliberately continues the fundamental studies emphasizing the chemistry of phenothiazine derivatives initiated by distinguished predecessors namely Professor I. A. Silberg and Professor V. Farcasan. In this regard, new phenothiazine derivatives with interesting stereochemical assemblies suitable for coordination chemistry, useful intermediates in the regioselective preparation of higher substituted phenothiazine derivatives and new chromophore/fluorophore structures were designed, synthesized and structurally characterized with the aim of their exploitation as platforms for the study of theoretical principles and applications in different areas of chemistry, physics, material science, biology and medicine.
Much effort was spent in optimizing the synthetic paths in terms of reaction selectivity, yields and energy consumption. Exploitation of advantages induced by the dielectric heating allowed us the development of facile, rapid and more ecofriendly microwave assisted synthetic protocols for many of the new phenothiazine derivatives.
New chromophore architectures comprising arrays of phenothiazine and (hetero)aromatic units were designed as suitable candidates for photoinduced energy transfer systems and fluorescence- emitting materials by modulating the nature and position of the substituent, the linker conjugation and/or metal insertion. Their structure-photophysical property relationships were unambiguously assigned by means of both appropriate experimental spectroscopic evidences and theoretical calculations. Detailed investigations of the electronic properties performed by means of cyclic voltammetry, absorption and fluorescence spectroscopy illustrated the possibility of fine tuning of typical properties such as: shifts of oxidation potentials and position of absorption bands, variable emission quantum yields and exceedingly large Stokes shifts.
The properties of the very potent pharmacophoric phenothiazine core embedded in the structure of the synthesized derivatives confirmed promising applications in the field of medicinal chemistry.