A one-step straightforward strategy has been developed to incorporate free imidazole molecules into a highly stable metal-organic framework (NENU-3, ([Cu(BTC)(HO)][HPWO])·Guest). The resulting material Im@(NENU-3) exhibits a very high proton conductivity of 1.82 × 10 S cm at 90% RH and 70 °C, which is significantly higher than 3.16 × 10 S cm for Im-Cu@(NENU-3a) synthesized through a two-step approach with mainly terminal bound imidazole molecules inside pores. Single crystal structure reveals that imidazole molecules in Im-Cu@(NENU-3a) isolate lattice water molecules and then block proton transport pathway, whereas high concentration of free imidazole molecules within Im@(NENU-3) significantly facilitate successive proton-hopping pathways through formation of hydrogen bonded networks.

Negative thermal expansion (NTE), whereby lattices contract upon heating, is of considerable interest for its wide applications in many fields. Molecular materials have been widely investigated as catalysts, sensors, etc., which usually endure temperature vibration. NTE can become a substantial means for controlling the coefficients of thermal expansion. Molecular materials possess plentiful structures and can be easily decorated, making them ideal platforms for thermal expansion modification. In this feature article, we provide an overview of the recent developments in utilizing NTE in molecular materials and summarize some mechanisms leading to NTE. The discussion of NTE in molecular materials concerns many factors, including transverse vibration, geometric flexibility, host-guest interactions, spin crossover, molecular packing rearrangement and molecular conformational changes.

Partial least squares calibration models are compared for the measurement of glucose, lactate, urea, ascorbate, triacetin, and alanine in aqueous solutions from single-beam spectra collected over the first overtone (6500-5500 cm(-1)) and the combination (5000-4000 cm(-1)) regions of the near-infrared spectrum. Spectra are collected under two sets of conditions with one designed for combination spectra and the other designed for first overtone spectra. As part of the optimization of conditions, an exponential function is presented that accurately characterizes the strong dependency between spectral quality and sample thickness. Sample thickness set for the first overtone and combination spectra are 7.5 and 1.5 mm, respectively. Independent calibration models are established for each solute from both combination and first overtone spectra. Direct comparison reveals superior performance by models generated from combination spectra, particularly for glucose and urea. Standard error of prediction (SEP) values are 1.12 and 0.45 mM for glucose models generated from first overtone and combination spectra, respectively. SEP values for urea are 7.33 and 0.10 mM for first overtone and combination spectra, respectively. Such high SEP values for urea with first overtone spectra correspond to an inability to quantify urea from these spectra because of a lack urea-specific molecular absorption features in this spectral region. Net analyte signal (NAS) is used to quantify the degree of selectivity provided within the first overtone and combination spectral regions. The superior selectivity of combination spectra is confirmed by comparing the length of the NAS vectors for each matrix component.

Red-emitting nitride phosphors excited with blue light have great potential for the fabrication of warm white light-emitting diodes (WLEDs). Chemical composition and structural modification are generally adopted to optimize the photoluminescence behaviors of the targeted phosphors. Herein, on the basis of the famous CaAlSiN3 phosphors, Eu(2+)-doped (Ca(1-x)Li(x))(Al(1-x)Si(1+x))N3 solid solutions via the cations' cosubstitution of (CaAl)(5+) pair by (LiSi)(5+) pair are successfully synthesized by a solid state reaction, and the lattice parameters show a linear decrease with chemical compositions suggesting the formation of the isostructural phase relationship. Four types of coordinated structure models, corresponding to different coordination environments of Eu(2+), are proposed over the course of structural evolution, which induces different structural rigidity and stability, and then they are responsible for three-stage changes of emission spectra of Eu(2+) in (Ca(1-x)Li(x))(Al(1-x)Si(1+x))N3 solid solution.