Solvent-Free Thermal Synthesis of Luminescent Dinuclear Cu(I) Complexes with Triarylphosphines.

Luminescent [Cu2I2(pyrpy)2(PR3)2] complexes (pyrpy = 4-pyrrolidinopyridine; PR3 = triphenylphosphine (1), tri- m-tolylphosphine (2), tri- p-tolylphosphine (3)) were prepared by solution reactions and a rarely reported solvent-free thermal method. X-ray structure analyses reveal that complexes composed of dinuclear {Cu2I2} cores surrounded by two PR3 and two pyrpy ligands were formed. Although the melting point of pyrpy is the lowest among the organic units used in this study, the temperature required to form the luminescent dinuclear complex, prepared by the thermal synthesis method, depended strongly on the PR3 moiety. Two of the three complexes (1 and 3) were successfully prepared by the solvent-free thermal method. Complexes 1-3 exhibited blue emissions at around 450 nm with moderately high quantum yields (Φ) of 0.24, 0.31, and 0.51, respectively. Emission-lifetime measurements and time-dependent density functional theory (TD-DFT) calculations suggest thermally activated delayed fluorescence (TADF) in each complex. This solvent-free thermal synthesis of TADF materials represents a promising method for the preparation of luminescent layers directly onto substrates of thin-layer electronic devices, such as organic light-emitting diodes.

In Situ Combustion Synthesis of Gr/h-BN Composites and Its Passive Heat Dissipation Application.

To enhance the infrared radiation efficiency and the heat transfer performance simultaneously, graphene (Gr) was synthesized in situ on hexagonal boron nitride (h-BN) to prepare Gr/h-BN composites by a scalable combustion synthesis in CO2 atmosphere using Mg as sacrificial solder. The synthesized Gr/h-BN composites were added in polydimethylsiloxane polymer to prepare composite coatings, which show an infrared emissivity greater than 0.95 and a through-plane thermal conductivity up to 2.584 W·m-1·K-1. When functioning on an Al heatsink, such a composite coating can reduce the temperature by as much as 21.7 °C. Meanwhile, the composite coating exhibits superior adhesion on the Al substrate. Therefore, Gr/h-BN composite coatings with noteworthy infrared radiation and thermal conductivity are expected to be a promising candidate for heat dissipation applications.

Using real-time UV-visible spectrophotometer to assess an Al-Zn-Mg-Cu alloy's dissolution in acidic solution.

Applicability and limitations of using online non-destructive ultraviolet-visible (UV-vis) spectrophotometer to monitor the dissolution of an Al-Zn-Mg-Cu alloy in HCl-containing solution were studied. Inductively coupled plasma atomic emission spectrometry results indicate that the spectrum absorbance at 252 nm is mainly attributed to Cu-containing complexes. Surprisingly, an hours-long 'induction' period was observed from UV-vis results. This is not a real indicator of induction for Al dissolution as revealed by electrochemical impedance spectrum, actually it reflects the alloy's galvanic corrosion nature that Cu species are released after Al, Zn and Mg species.