Sn(ii) induced concentration dependent dynamic to static excimer conversion of a conjugated naphthalene derivative

Abstract

The X-ray structurally characterized naphthalene appended diformyl-p-cresol derivative (L) selectively detects Sn²⁺ by both colorimetric and fluorescence methods. In the presence of Sn²⁺, L exhibits a monomer emission at 420 nm along with a strong red excimer emission at 582 nm in acetonitrile. The excimer formation highly depends on Sn²⁺ concentration. The dynamic excimer, observed with up to 2.5 equivalents of Sn²⁺, gradually converts to a static form above 2.5 equivalents of Sn²⁺. Moreover, in a different solvent media, viz. in aqueous methanol, L can also detect Al³⁺ through the generation of intense green fluorescence. The photophysical interactions are rationalized by ¹H NMR, mass spectra, steady state and lifetime fluorescence measurements. DFT studies support the experimental findings.