Multi-Stimuli Responsive Luminescence and Domino Phase Transition of Hybrid Copper Halides with Nonlinear Optical Switching Behavior

Although phase transition materials (PTMs) under external stimuli are of great research interest duo to their rich potential applications, it is still challenging to explore multi-responsive PTMs. Herein, two different phases of organic–inorganic hybrid copper-based halides, α- and β-Gua₃Cu₂I₅ (Gua⁺=CN₃H₆⁺), were synthesized by solvent evaporation method, which they crystalize in the noncentrosymmetric space group Fdd2 with zero-dimensional structure and centrosymmetric space group C2/c with one-dimensional metal-halogen framework, respectively. Interestingly, it is firstly demonstrated that Gua₃Cu₂I₅ simultaneously possesses reversible PL conversion and NLO switching properties in response to thermal stimulus. Strikingly, apart from heat, its structural phase transition can also be triggered by crystalline-phase-recognition (CPR) and mechanical force. These new findings may pave a path for future exploration of PTMs with multiple physical properties.     

Nonlinear Optical Glass-Ceramic From a New Polar Phase-Transition Organic-Inorganic Hybrid Crystal

Melt-quenched glasses of organic–inorganic hybrid crystals, i.e., hybrid glasses, have attracted increasing attention as an emerging class of hybrid materials with beneficial processability and formability in the past years. Herein, we present a new hybrid crystal, (Ph₃PEt)₃[Ni(NCS)₅] ( 1 , Ph₃PEt⁺=ethyl(triphenyl)phosphonium), crystallizing in a polar space group P1 and exhibiting thermal-induced reversible crystal-liquid-glass-crystal transitions with relatively low melting temperature of 132 °C, glass-transition temperature of 40 °C, and recrystallization on-set temperature of 78 °C, respectively. Taking advantage of such mild conditions, we fabricated an unprecedented hybrid glass-ceramic thin film, i.e., a thin glass uniformly embedding inner polar micro-crystals, which exhibits a much enhanced intrinsic second-order nonlinear optical effect, being ca. 25.6 and 3.1 times those of poly-crystalline 1 and KH₂PO₄, respectively, without any poling treatments.     

Phosphorescent Sensor Approach for Non-Destructive Measurement of Oxygen in Packaged Foods: Optimisation of Disposable Oxygen Sensors and their Characterization Over a Wide Temperature Range

ABSTRACT

Phosphorescent oxygen sensors were evaluated for their suitability as a non-destructive method of measuring oxygen in packaged foods. Using phosphorescent phase measurements, characteristics of several types of disposable oxygen sensors were studied in order to optimize sensor chemistry, fabrication technology and performance. The optimal sensor was characterized in both the gas phase and in the liquid phase, over a temperature range of –17°C ? +30°C and oxygen concentrations between 0 and 21 kPa. Calibrations, analytical equations and temperature coefficients were obtained, which enabled accurate quantitation of oxygen and correction of optical measurements for sample temperature variations. For disposable sensor elements the resolution of the system at 22°C was about ±0.02 kPa and ±0.5 kPa at 0 and 21 kPa oxygen respectively, and in continuous monitoring mode - ±0.0054 kPa and ±0.081 kPa oxygen, respectively. Results of the use of the oxygen sensors in food packaging applications and practical recommendations are presented.     

A Borinic Acid Polymer with Fluoride Ion‐ and Thermo‐responsive Properties that are Tunable over a Wide Temperature Range

A new type of smart borinic acid polymer with luminescence and multiple stimuli‐responsive properties is reported. In DMSO with small amounts of water, the homopolymer PBA shows a tunable upper critical solution temperature (UCST). As the amount of water increases from 0 to 2.5 % (v/v), the UCST rises linearly from 20 °C to 100 °C (boiling point of water). Thus, the thermal responsive behavior can be tuned over a wide temperature range. Furthermore, polymer solutions in DMSO show a reversible response to fluoride ions, which can be correlated to the presence of the Lewis acidic borinic acid groups. Upon addition of fluoride, the polymer becomes soluble because the functional R₂BOH groups are converted into ionic [R₂BF₂]^? groups, but turns insoluble again upon addition of H₂O, which reverses this process.     

Synthesis, Structure and Secondorder Nonlinear Optical Activities of a New Tungsten（0） Compound with Pyridine-2-thiolato Ligand, [Et4N][W（pyS）（CO）4] （pys = C5H4NS^-）

The reaction of W(CO)6 with pyOSNa (C5-H4NOSNa) and Et4NCl in MeCN affords a new tungsten(0) complex [Et4N][W(pyS)(CO)4] 1 (Mr.= 536.29).The crystal and molecular structures have been determined by X-ray single-crystal diffraction.Complex 1 crystallizes in the orthorhombic system,space group P212121 with a = 8.2429(5),b = 9.1045(4),c =26.8851(14) (A),β = 90.00°,V= 2017.66(18) (A)3,Z = 4,Dc.= 1.765 g/cm3,μ = 58.51 cm-1,F(000) =1048,the final R = 0.0204 and wR = 0.0400 for 4432 observed reflections with I ＞ 2σ(I).X-ray structure analysis revealed that the molecule is acentric and has large first-order hyperpolarizability (7.2 × 10-30 esu),so it could be an IR second-order nonlinear optical candidate material.