Amino-Terephthalonitrile and Amino-Terephthalate-Based Single Benzene Fluorophores - Compact Color Tunable Molecular Dyes for Bioimaging and Bioanalysis.

This review article discusses the emerging amino-terephthalonitrile (Am-TN) and amino terephthalate-based single benzene fluorophores (SBFs) for their highly emissive nature and potential for numerous technical applications. Am-TN-SBFs are a new class of SBFs having amine as the electron donating (EDG) and dinitrile as the electron withdrawing group (EWG). The beauty of these Am-TN-SBFs lies in excellent intramolecular charge transfer between the EDG and EWG.

Conversion of amino-terephthalonitriles to multi-substituted single benzene fluorophores with utility in bioimaging.

Substitution of two fluorine atoms of the tetrafluoroterephthalonitrile (TFTN) ring ( to each other) by amine nucleophiles through SAr chemistry is achievable. However, tri- and tetra-substitution towards multi-substituted single benzene fluorophores (SBFs) is harder due to increased electron richness of the TFTN moiety. Tertiary amine donors promote the molecule towards such multi-substitution guided by the steric obstruction to intramolecular charge transfer to the TFTN ring.

Diamino-Terephthalonitrile-based Single Benzene Fluorophores Featuring Strong Solution State Fluorescence and Large Stokes Shifts.

1°- and 2°-amines react with tetrafluoroterephthalonitrile through SAr chemistry, creating the strongly emissive paradiamino-terephthalonitrile type single benzene fluorophores. The regioselectivity of reaction is dictated by the sterics of the initial secondary amine adduct. The molecules exhibit strong green-yellow emission and large (nearly 150 nm) Stokes shifts.

Amino-Terephthalonitrile-Based Single Benzene Fluorophores with Large Stokes Shifts and Solvatochromic Behavior.

We have synthesized a small library of blue-to-green emissive single benzene-based fluorophores (SBFs) in a short synthetic sequence. The molecules exhibit good Stokes shift in the range of 60-110 nm and select examples also possess very high fluorescence quantum yields of up to 87%. Theoretical investigations into the ground state and excited state geometries of many of these compounds reveal that good degree of planarization between the electron donor secondary amines and electron accepting benzodinitrile units can be achieved under certain solvatochromic conditions, giving rise to the strongly fluorescent behavior.

Spatial and temporal volatile organic compound response of select tomato cultivars to herbivory and mechanical injury.

Plants resist an insect or pathogen attack through a range of direct and indirect defense signals. Vegetable crop plants constitutively synthesize and store a battery of volatiles implicated in defense against herbivores. We examined the effect of herbivory (Spodoptera litura Fab.