NIR-II Organic Photothermal Cocrystals with Strong Charge Transfer Interaction for Flexible Wearable Heaters

The organic cocrystal strategy has provided a convenient and efficient platform for preparing organic photothermal materials.However,the rapidly directional preparation of cocrystals with desirable photothermal properties remains challenging due to a lack of suitable design ideas.Here,two new photothermal cocrystals,MTC and MFC,based on acceptor molecules(TCNQ and F4TCNQ)with different electron-withdrawing capacities were quickly prepared by the coprecipitation method,aiming to explore the effect of charge transfer(CT)interaction on photothermal properties.Compared with MTC,the stronger intermolecular CT interaction in MFC facilitates extending the absorption range(from the NIR-I to the NIR-II region)and enhancing the non-radiative transition process.Under the 808 nm laser irradiation,the photothermal conversion efficiency(PCE)of MFC is 54.6%,whereas MTC displays a mere 36.8%.The MFC cocrystal was further combined with a flexible polymer substrate(HPDMS)to prepare a flexible wearable heater(HPDMS@MFC),which exhibits excellent NIR-II photothermal performance.This work points out a research direction for the rapid assembly of efficient photothermal cocrystals and additionally provides an extensive application prospect for organic photothermal cocrystals in the field of wearable devices.

Syntheses, Cytotoxicity and Properties of CO Releasing Molecules Containing Acetyl Salicylamide-3-pyridine

A series of CO-releasing molecules [M（CO）5L] （M=Cr, W, Mo, L=acetyl salicylamide 3-pyridine, 1--3; L= N,N-dimethyl-4-pyridine, 4-6; L=nicotinamide, 7--9; L=4-CHO-pyridine, 10--12） were synthesized. And in this paper, we have investigated mainly cytotoxicity and properties of the CO-releasing molecules containing acetyl salicyamide-3-pyridine, namely complexes 1--3. The stability of complexes 1 and 2 was evaluated by means of UV-Vis spectroscopy and 1H NMR spectra. The results indicate complexes 1 and 2 were stable in methanol and acidic aqueous solution, but unstable and decayed in basic media （pH 10.0）. Among all the complexes, complex 2 was the slowest CO-releaser, and its half-life was 73.8 min. Complex 9 containing nicotinamide was the fastest CO-releaser with half-life only 6.5 min. In addition, cytotoxic effects of all the complexes on the proliferation of fibroblast line were assayed by MTT. Among all the complexes, the IC50 of complex 1 was 6 μmol/L, revealing complex 1 possessed stronger antiproliferative activity than the control. Analysis by Flow cytometry revealed that complex 1 arrested Hela cells in S phase while complexes 2 and 8 arrested in G2/M phase. Cell apoptosis caused by the complexes mainly occurred in ＂Late apoptosis＂.

Amplified spontaneous emission, optical waveguide and polarized emission based on 2,5-diaminoterephthalates

A series of 2,5-diaminoterephthalates with a simple structure were synthesized through one-step reaction, and their bar-shaped single crystals with a large size and a smooth surface have been obtained via the solvent-evaporation method. These crystals exhibit bright emission with fluorescence quantum yields higher than 0.2. They display the waveguide property, and low optical loss coefficients for waveguide have been determined for the crystal of one compound. In addition, the crystal can cause linear polarization of the light emitted from it, with a high polarization contrast of 0.70. Most importantly, these crystals can realize amplified spontaneous emission （ASE）, including the red ASE, with appreciable energy thresholds of 72-198 kW/cm^2 and high gain coefficients, which suggests the potential of these crystals for the application in organic solid-state lasers.

An Optical Waveguiding Organic Crystal with Phase-Dependent Elasticity and Thermoplasticity over Wide Temperature Ranges

Elastic or plastic bendable organic crystals have attracted increasing attention in the field of crystal engineering.For the application of flexible materials,the applicable temperature range can not be ignored.However,studies on the flexible organic crystals reported so far have not involved the effect of temperature on the mechanical properties of these materials.Here,organic crystals of 9,10-bis(phenylethynyl)anthracene with phase-dependent mechanical properties over wide temperature ranges are reported.

Infrared stimulated emission with an ultralow threshold from low-dislocation-density InN films grown on a vicinal GaN substrate

Near-infrared stimulated emission from a high-quality InN layer under optical pumping was observed with a threshold excitation power density of 0.3 and 4 kW cm^(−2) at T=8 and 77 K,respectively.To achieve such a low threshold power density,vicinal GaN substrates were used to reduce the edge-component threading dislocation(ETD)density of the InN film.Cross-sectional transmission electron microscopy images reveal that the annihilation of ETDs can be divided into two steps,and the ETD density can be reduced to approximately 5×10^(8) cm^(−2) near the surface of the 5-μm-thick film.The well-resolved phonon replica of the band-to-band emission in the photoluminescence spectra at 9 K confirm the high quality of the InN film.As a result,the feasibility of InN-based photonic structures and the underlying physics of their growth and emission properties are demonstrated.