Five new, star-shaped compounds containing a central oligo­(phenylenevinylene) core carrying six alkoxy chains were synthesized, and with varying alkyl chains the changes in their supramolecular assembly were explored by small and wide-angle X-ray scattering (SAXS/WAXS) studies. For the shortest peripheral alkoxy chain (3.1; R = 3,7-dimethyl octyl) lamellar stacking was favored, whereas with increasing the alkoxy chain length (3.2, 3.3, 3.4, and 3.5; n-C12H25, n-C14H29, n-C16H33, n-C18H35) columnar rectangular (Colr) assembly was observed. The compound with branched peripheral chains (3.1) with lamellar assembly did not exhibit organogelation, but four other compounds (3.2, 3.3, 3.4 and 3.5) showed the ability to gelate in nonpolar solvents at a lower concentration even in less than 1 wt % (qualifying it as a supergelator), possibly due to their existence in the Colr packing having strong π–π interactions. This occurrence is less observed, in comparison to previous reports where supergelation happened mostly via H-bonding interactions. The hierarchical self-assembly of gels was investigated using transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and X-ray diffraction studies. Interestingly, Colr packing was retained even in the gel state also. Rheological measurements performed on the samples displayed mechanical robusticity of these gels. All the compounds showed blue luminescence in solution as well as in thin-film states. The electroluminescent properties of the compound 3.3 were examined as emissive layers in organic light emitting diodes (OLEDs). It was explored by fabricating in OLED devices either as a host or dopant-emitters in the 4,4′-bis­(N-carbazolyl)-1,1′-biphenyl host with different concentrations 1, 3, 5, and 7 wt %. The device fabricated with 1 wt % revealed the best electroluminescence performance with maximum luminescence, current efficiency, power efficiency, and external quantum efficiency.

The systematic investigation of the interaction of a new class of molecular materials with proteins through structure-optical signaling relationship studies has led to the development of efficient fluorescent probes that can detect and quantify serum albumins in biofluids without causing any denaturation.

Development of a highly photostable, renal clearable, and nontoxic new NIR probe (CyG) for precise quantification of albumin in different biofluids and liver targeted in vivo albumin visualization is demonstrated. CyG's inherent property to interact selectively with albumin among different biomolecules in intracellular environment with high degree of sensitivity helps CyG in targeted liver imaging. In addition to its long excitation/emission wavelengths (λ = 740 nm, λ = 804 nm), which are much above the biological tissue opaque window (400-700 nm) ensuring better photon penetration, diminished tissue autofluorescence and high contrasts, its molecular mass and size are far below the renal cutoff and hence, CyG qualifies as imaging material for clinical studies. We anticipate that CyG will provide new strategies to overcome the pitfall of present day albumin detection methods as well as accelerate the detection process at relatively lower costs without compromising the accuracy of detection. Moreover, the renal excretion kinetic and intrahepatic albumin binding affinity of CyG can further be used to differentiate between fatty liver from healthy liver in an experimentally arrived mouse model using noninvasive technique.

Selective staining of human serum albumin protein in gel electrophoresis over wide range of other protein(s) is extremely important because it contains more than 60% volume of serum fluid in human body. Given the nonexistence of suitable dye materials for selective staining of serum albumins in gel electrophoresis, we report a new class of easy synthesizable and low molecular weight staining agents based on 3-amino-N-alkyl-carbazole scaffold for selective staining of serum albumins in solid phase. A detailed structure-efficiency relationship (SER) study enabled us to develop two such potent functional molecular probes which stain both human and bovine serum albumin selectively in gel electrophoresis in the presence of other proteins and enzymes. The present gel staining process was found to be very simple and less time-consuming as compared to the conventional coomassie blue staining which in turn makes these probes a new class of serum albumin-specific staining materials in proteome research. Moreover, these molecular lumino-materials can detect serum albumins at subnanomolar level in the presence of broad spectrum of other proteins/enzymes in aqueous buffer (99.9% water, pH = 7.3) keeping the protein secondary structure intact. Our experimental and the docking simulation results show that these probes bind preferentially at 'binding site I' of both the serum proteins.

Enantioselective recognition of chiral amines through gel formation and collapse.