Synthesis Of Pyridazine And Tetrathiafulvalene-amino Acid Study On Gelation And Gel Properties

Supramolecular gels,in which small gelator molecules selfassembled into entangled nanostructures to immobilize the solvents through non-covalent intermolecular interactions,including hydrogen-bonding,?-? stacking,hydrophobic interactions,van der Waals forces,electrostatic interactions,metal ion toligand coordination,and charge-transfer(CT)interactions,have attracted much attention in materials science.In the family of supramolecular gelators,low-molecular-weight organogelators(LMOGs)are typically small molecules,which show higher superiority because of their accurate molecular weight,easy modification,multifarious nanostructures,and stimuli-responsive properties.Due to the weak and reversible nature of the non-covalent interactions,these supramolecular gels are responsive and readily tunable by mechanical,light,thermal,and chemical stimuli.Therefore,supramolecular gels have attracted immense research interest as they possess ample applications in light harvesting,tissue engineering,shape memory devices,drug delivery,photovoltaics,etc.As one of the most famous organic ? electron-donors,tetrathiafulvalene(TTF)and its derivatives self-assemble via cooperative S…S and ?-? stacking interactions in the neutral state and have been widely investigated as molecular metals in crystalline and supramolecular states In previous reports in the literature,based on the tetrathiafulvalene(TTF)gel factor are in the majority with linear type.And based on the tetrathiafulvalene(TTF)T organic gel factor is rarely reported.A series of pyridazine coupled tetrathiafulvalene T-shaped derivatives with varying amino acid moieties have been synthesized and their gelation properties were studied in various organic solvents.Among these derivatives,two gelators bearing glycine or phenylalanine units display efficient gelation in aromatic and polar solvents.Interestingly,these gelators,except for the gelator containing two tryptophan units,are able to gel DMF via a solution-to-gel transformation when triggered with sonication for less than 20 s or cooled below zero.A number of experiments revealed that these gelator molecules self-assembled into elastically interpenetrating three-dimensional network structures with nanofibers over tens of micrometers in length and all nanofibers showed obvious helical structures.The formed gels undergo a reversible gel-sol phase transition upon exposure to external stimuli,such as temperature,sonication and chemical oxidation/reduction.Importantly,gelators could form the binary gel with C60 in toluene and the formed binary gel also showed a helical nanofiber morphology.A driving force of the binary gel,instead of the ?-?stacking and S-S interactions,is attributed to the donor-acceptor interaction between the MPDTTF unit and C60,which is confirmed by ESR spectral data.Moreover,the gel system exhibits a strong gel-induced enhanced emission(GIEE)that the neighbouring chromophores are stacked in J-aggregation mode,and the fluorescence was effectively quenched by the introduction of C60.Furthermore,these gelators showed efficient phase-selective gelation properties at room-temperature,and the gels could adsorb cationic dyes from water,indicating their possible applications in wastewater treatment.