Modulating nanostructure morphology and mesomorphic properties using unsaturation in cardanol-azo benzenes.

Herein, we report the synthesis and self-assembly of a new class of amphiphilic azo dyes derived from a plant-based phenol, cardanol. Analysis of the self-assembly of these new azo derivatives was intriguing, and they exhibit some unique nanostructures, such as bicelles and microgel-like structures, and smectic-type thermotropic mesophases.

Novel semisquaraine regioisomers: isolation, divergent chemical reactivity and photophysical properties.

A zwitterionic semisquaraine 1,3-regioisomer which exhibits distinct photophysical properties and chemical reactivity was isolated. Uniquely, this isomer has been identified as the reactive intermediate in the squaraine dye formation reaction rather than the neutral 1,2-isomer and opens up new avenues for the synthesis of novel dyes for optoelectronic applications.

Self-standing, metal nanoparticle embedded transparent films from multi-armed cardanol conjugates through in situ synthesis.

We report multi-armed/dendritic molecules having unsaturated side chains for generating scratch-free, self-standing cross-linked transparent films with embedded metal nanoparticles via autoxidation induced in situ synthesis.

Infrared absorbing croconaine dyes: synthesis and metal ion binding properties.

Quinaldine-based croconaine dyes synthesized by the condensation reaction between croconic acid and the respective quinaldinium salts are described. These dyes exhibit absorption maximum in the infrared region (840-870 nm) with high molar extinction coefficients (1-5 x 10(5) M(-1) cm(-1)) and have very low fluorescence quantum yields. Upon binding to divalent metal ions, these dyes were found to form complexes with a 2:1 stoichiometry having high association constants of the order of 10(11)-10(14) M(-2), while the monovalent metal ions showed negligible affinity.

Chiral supramolecular assemblies of a squaraine dye in solution and thin films: concentration-, temperature-, and solvent-induced chirality inversion.

We prepared novel cholesterol-appended squaraine dye 1 and model squaraine dye 2 and investigated their aggregation behavior in solution and thin films using photophysical, chiroptical, and microscopic techniques. Investigations on the dependence of aggregation on solvent composition (good/poor, CHCl3/CH3CN) demonstrated that squaraine dye 1 forms two novel H-type chiral supramolecular assemblies with opposite chirality at different good/poor solvent compositions. Model compound 2 formed J-type achiral assemblies under similar conditions.

Dual-mode semisquaraine-based sensor for selective detection of Hg2+ in a micellar medium.

[reaction: see text] A novel chemosensor based on semisquaraine dye (SSQ) for selective detection of Hg2+ is described. SSQ is obtained in quantitative yields from the reaction between squaric acid and 6-ethoxy-2-quinaldinium iodide. SSQ in combination with surfactant shows a dual chromogenic and fluorogenic response selectively toward Hg2+ as compared to Li+, Na+, K+, Ag+, Ca2+, Mg2+, Zn2+, Pb2+, Cd2+, Cu2+, and Fe3+ due to the soft acid nature and size of the mercuric ion.

Synthesis of new cholesterol- and sugar-anchored squaraine dyes: further evidence of how electronic factors influence dye formation.

[reaction: see text] Synthesis of new quinaldine-based squaraine dyes linked to cellular recognition elements that exhibit near-infrared absorption (>740 nm) are described. Both product analysis and theoretical calculations substantiate the interesting electronic effects of various substituents in the dye formation reaction. These results are useful in the synthesis of symmetrical and unsymmetrical squaraine dyes that can have potential biological and photodynamic therapeutical applications.

Synthesis of novel quinaldine-based squaraine dyes: effect of substituents and role of electronic factors.

[reaction: see text] Condensation of squaric acid with quinaldinium salts containing electron-donating substituents gave only the semisquaraines. However, with salts possessing electronegative and electron-withdrawing groups, the squaraine dyes were isolated in quantitative yields. The semisquaraines formed undergo condensation with highly nucleophilic salts yielding the unsymmetrical squaraine dyes.