Silane‐bridged diphosphine ligand for palladium‐catalyzed ethylene oligomerization

In this study, bis(diphenylphosphinemethyl)dimethyl silane ( L1 ) and its palladium(II) halide complex, L1 /PdCl₂ ( C1 ), were synthesized and characterized. Single‐crystal X‐ray analysis of the complex revealed bidentate coordination at the Pd center. In combination with methylaluminoxane (MAO) as co‐catalyst, C1 exhibited excellent catalytic activity and selectivity for ethylene dimerization toward butene. The maximum catalytic activity obtained from the C1 /MAO system for ethylene dimerization to yield butenes was 7.33 × 10⁵ g/(mol_Pd · h). The selectivity toward butene remained stable and high (> 96%) over the various conditions.     

Mg(ClO4)2-catalyzed intramolecular allylic amination: application to the total synthesis of demethoxyfumitremorgin C

A Mg(ClO₄)₂-catalyzed intramolecular amination of allylic alcohols with carbamate or sulfonamide nucleophiles to form substituted piperidine and pyrrolidine derivatives has been developed. This method has been successfully applied to the total synthesis of demethoxyfumitremorgin C.     

Optimizing Optoelectronic Properties of Pyrimidine‐Based TADF Emitters by Changing the Substituent for Organic Light‐Emitting Diodes with External Quantum Efficiency Close to 25 % and Slow Efficiency Roll‐Off

A series of green butterfly‐shaped thermally activated delayed fluorescence (TADF) emitters, namely PXZPM , PXZMePM , and PXZPhPM , are developed by integrating an electron‐donor (D) phenoxazine unit and electron‐acceptor (A) 2‐substituted pyrimidine moiety into one molecule via a phenyl‐bridge π linkage to form a D –π–A–π–D configuration. Changing the substituent at pyrimidine unit in these emitters can finely tune their emissive characteristics, thermal properties, and energy gaps between the singlet and triplet states while maintaining frontier molecular orbital levels, and thereby optimizing their optoelectronic properties. Employing these TADF emitters results in a green fluorescent organic light‐emitting diode (OLED) that exhibits a peak forward‐viewing external quantum efficiency (EQE) close to 25 % and a slow efficiency roll‐off characteristic at high luminance.     

Effects of longitudinal fire source locations on the maximum temperature and longitudinal temperature decay in a mountain tunnel with vertical shaft: an experimental investigation and empirical model

Journal of Thermal Analysis and Calorimetry - Few investigations have focused on the influence of longitudinal fire source location on the temperature profile of smoke induced by fire in a tunnel...     

Uncertain random data envelopment analysis for technical efficiency

Fuzzy Optimization and Decision Making - Data envelopment analysis (DEA) is a classical and prevailing tool for estimating relative efficiencies of multiple decision making units (DMUs). However,...     

pH‐ and Thiol‐Responsive BODIPY‐Based Photosensitizers for Targeted Photodynamic Therapy

A diiodo distyryl boron dipyrromethene (BODIPY) core was conjugated to two ferrocenyl quenchers through acid‐labile ketal and/or thiol‐cleavable disulfide linkers, of which the fluorescence and photosensitizing properties were significantly quenched through a photoinduced electron‐transfer process. The two symmetrical analogues that contained either the ketal or disulfide linkers could only be activated by a single stimulus, whereas the unsymmetrical analogue was responsive to dual stimuli. Upon interaction with acid and/or dithiothreitol (DTT), these linkers were cleaved selectively. The separation of the BODIPY core and the ferrocenyl moieties restored the photoactivities of the former in phosphate buffered saline and inside the MCF‐7 breast cancer cells, rendering these compounds as potential activable photosensitizers for targeted photodynamic therapy. The dual activable analogue exhibited the greatest enhancement in intracellular fluorescence intensity in both an acidic environment (pH 5) and the presence of DTT (4 mm ). Its photocytotoxicity against MCF‐7 cells also increased by about twofold upon preincubation with 4 mm of DTT. The activation of this compound was also demonstrated in nude mice bearing a HT29 human colorectal carcinoma. A significant increase in fluorescence intensity in the tumor was observed over 9 h after intratumoral injection.