ABSTRACT
A series of platinum(II) acetylide complexes with elaborate long-chain pyridine-2,6-dicarboxamides was synthesized. These metal complexes are capable of immobilizing organic solvents to form luminescent metallogels through a combination of intermolecular hydrogen bonding, aromatic π-π, and van der Waals interactions. Fibrillar morphologies were identified by TEM for these metallogels. Unique photophysical properties associated with the sol-to-gel transition have been disclosed with luminescence enhancement at elevated temperatures, which is in sharp contrast to typical thermotropic organogels or metallogels reported in the literature. Such unusual luminescence enhancement is attributed to the increased degree of freedom at higher temperatures that results in the formation of favorable molecular aggregates in the excited state through enhanced aromatic π-π and metallophilic Pt(II)···Pt(II) interactions. Structurally similar Pt-bp3 is not able to gel any common organic solvents. The inability of Pt-bp3 to form gels illustrates the importance of gelation to the macroscopic photophysical properties; Pt-bp3 does not show emission enhancement at elevated temperatures due to its low tendency to form strong aggregates in the ground state.
Subject(s)
Dicarboxylic Acids/chemical synthesis , Gels/chemical synthesis , Organometallic Compounds/chemical synthesis , Platinum/chemistry , Pyridines/chemical synthesis , Dicarboxylic Acids/chemistry , Gels/chemistry , Luminescence , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Structure , Organometallic Compounds/chemistry , Pyridines/chemistryABSTRACT
An energy upconversion system based on triplet-triplet annihilation exploiting an organic triplet sensitizer is devised and has achieved a white-light emission with a low power laser excitation.
ABSTRACT
A series of new organogelators with pi-conjugated phenylethynyl framework featuring long-chain carboxamides have been synthesized. These organgelators have shown great ability to gel a variety of organic solvents to form stable organogels with the minimum gelation concentration as low as 0.1 wt %. Gelation is completely thermoreversible, and it occurs due to the aggregation of the organogelators resulting in the formation of a fibrous network via a combination of intermolecular hydrogen bonding, pi-pi stacking, and van der Waals interactions that is observed for the xerogels by TEM. The influence of sol-to-gel transition has been explored in detail by variable-temperature 1H NMR, UV-vis absorption, and fluorescence spectroscopy. Aggregation-induced enhanced emission has been observed in these organogelator molecules with an order of higher fluorescence quantum yields from solution to gels. In addition, some molecules also exhibit unique liquid crystalline properties over a large temperature range as revealed by DSC and POM studies.
ABSTRACT
A trinuclear star-shaped organometallic host with a pi-acidic interior cavity has been synthesized and this shows a strong anion-pi interaction with PF6-, as demonstrated in the crystal structure and colorimetric and luminescent responses with F- anion in solution.
