Article
Chemistry, Physical
Pedro G. Demingos, Naira M. Balzaretti, Andre R. Muniz
Summary: Density Functional Theory calculations reveal that carbon nanothreads derived from five-membered ring heterocyclic compounds such as thiophene, furan and pyrrole have superior stability, electronic properties, and mechanical performance compared to conventional nanothreads derived from benzene and pyridine. The presence of heteroatoms in the structure leads to significant variations in electronic band gap without compromising mechanical properties. These findings suggest that nanothreads derived from five-membered rings are suitable for traditional applications and potential candidates for new ones.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Nihal Khatiwoda, Aditya N. Panda
Summary: Evaluating and understanding optoelectronic properties of oligomers and polymers is important for materials science applications. In this study, thiophene-furan and thiophene-pyrrole oligomers were selected and calculations were carried out to determine the ground and excited state properties. The results showed minor differences between the two sets of oligomers and revealed that many of the excited states involved partial charge transfer.
CHEMICAL PHYSICS LETTERS
(2023)
Article
Chemistry, Organic
Kalyan Maram, Kowthalam Anitha, Reddymasu Sreenivasulu, Rudraraju Ramesh Raju
Summary: A series of N-(furan/thiophene/pyrrole-2-yl-(2-hydroxynaphthalen-1-yl)methyl) acetamide derivatives 4 have been synthesized via one-pot three-component synthesis using 2-naphthol 1, aldehydes 2, and amides 3 in the presence of DBU as a catalyst under reflux condition for 110-120 min. This method offers advantages of high yields, environmental friendliness, simplicity, short reaction times, and mild reaction conditions.
LETTERS IN ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
N. G. Chary, M. Gutta, K. Vidya
Summary: A green synthetic protocol was developed for the synthesis of novel 1H-pyrrole(furan, thiophene)-conjugated 1,4,6,7,8,9-hexahydro-5H-pyrazolo[3,4-b]quinolin-5-one derivatives in 80-85% yield by one-pot three-component reaction. The reaction was performed using [BMIM]OH as the ionic liquid medium at 75-80 degrees C for 110-120 min. High yields, low reaction times, gentle reaction conditions, and environmental friendliness were observed in this procedure.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Chow-Shing Lam, Kai-Chung Lau
Summary: A composite procedure based on CCSD(T)-F12 calculations was proposed to accurately predict the energy of carbon chain P molecules HCnH. The results show good agreement within a certain range and also demonstrate a thermochemical trend over the entire length.
JOURNAL OF PHYSICAL CHEMISTRY A
(2021)
Article
Engineering, Geological
Jing Ren, Huan He, Kai-Chung Lau, Kostas Senetakis
Summary: Research shows that artificially coating sand grains with iron oxides significantly alters the roughness and hardness of the grains, affecting inter-particle friction and normal contact stiffness. The friction coefficient of the coated specimens clearly depends on the magnitude of normal load and loading history, likely due to factors such as contact breakage, plowing damage, and surface debris buildup.
Article
Chemistry, Multidisciplinary
Huatian Shi, Runhui Liang, David Lee Phillips, Hung Kay Lee, Wai-Lun Man, Kai-Chung Lau, Shek-Man Yiu, Tai-Chu Lau
Summary: In this study, a stable manganese(V) nitridocomplex was synthesized and its molecular structure and reactivity were investigated. The findings suggest that this complex exhibits high reactivity and can serve as a nitrene transfer reagent.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Chao Wang, Yuzhuo Chen, Daijian Su, Wai-Lun Man, Kai-Chung Lau, Lianhuan Han, Liubin Zhao, Dongping Zhan, Xunjin Zhu
Summary: A new molecular electrocatalyst with highly dispersed CoN4 sites was synthesized for CO2 reduction reaction. The catalyst shortens the electron transfer pathway, accelerates the redox kinetics, and improves durability. Experimental results showed that it achieved high current density and CO conversion rate in commercial flow cells.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Inorganic & Nuclear
Yunling Pan, Miaomiao Zhou, Rui Wang, Dan Song, Shek-Man Yiu, Jianhui Xie, Kai-Chung Lau, Tai-Chu Lau, Yingying Liu
Summary: In this study, a new type of seven-coordinate ruthenium-iodosylbenzene complex was reported, which exhibited high reactivity towards various organic substrates through undergoing O-atom transfer and C-H bond activation reactions. The X-ray crystal structure of this complex revealed a distorted pentagonal bipyramidal geometry. This work provides insights for the development of new highly reactive oxidizing agents based on seven-coordinate geometry.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Jing Xiang, Yi Pan, Lu-Lu Liu, Li-Xin Wang, Huan Yang, Shun-Cheung Cheng, Shek-Man Yiu, Chi-Fai Leung, Chi-Chiu Ko, Kai-Chung Lau, Tai-Chu Lau
Summary: Although the oxidation of alcohols by metal nitrido complexes has not been studied extensively, this report demonstrates the visible-light-induced oxidation of primary and secondary alcohols to carbonyl compounds using a strongly luminescent osmium(VI) nitrido complex (OsN). The proposed mechanism involves the rate-limiting hydrogen-atom transfer from the alpha-carbon of the alcohol to OsN*. Attempts to catalytically oxidize alcohols by OsN* using PhIO as the terminal oxidant resulted in the formation of novel osmium(IV) iminato complexes where the nitrido ligand is bonded to a 6-carbon of the alcohol. Experimental and theoretical studies suggest that OsN* is reductively quenched by PhIO to generate highly active PhIO+ oxidant, which readily undergoes alpha- and 6- C-H activation of alcohols.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Jie Yan, Zi-Qi Feng, Yixin Wu, Dong-Ying Zhou, Shek-Man Yiu, Chin-Yiu Chan, Yi Pan, Kai Chung Lau, Liang-Sheng Liao, Yun Chi
Summary: Efficient blue phosphors for OLEDs remain challenging. Researchers have synthesized a series of Ir(III) complexes and studied their structures and photophysical properties to overcome this challenge. Some of the emitters can undergo interconversion without decomposition in a specific solvent. The synthesized Ir(III) complexes exhibit good luminescence properties and show potential for making blue OLEDs.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Hongyan Zhao, Yi Pan, Kai-Chung Lau
Summary: This article proposes a theoretical procedure for accurately determining the reduction potentials of three metallocene couples. By calculating the gas phase ionization energy and the solvation free energy, the one-electron reduction potential is obtained. The SMD model yields the best estimation for the solvation free energy and provides reliable values for the reduction potentials.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Optics
Yue Gao, Yi Pan, Shenyue Xu, Kai-Chung Lau, Hang Yuan, Zhenyu Yan, Dalong Guo, Dongmei Zhao, Xiaolong Zhu, Shuncheng Yan, Shaofeng Zhang, Zhongfeng Xu, Xinwen Ma
Summary: The three-body fragmentation of C2H23+ to H+ + C+ + CH+ resulting from CH and CC bond breaking is studied under 50-keV/u Ne8+ impact. All three fragments are detected in coincidence with a scattered projectile (either Ne7+ or Ne6+) using a reaction microscope, and their momentum vectors and kinetic energies are obtained. Four distinct structures are observed in the energy correlation spectra, indicating multiple fragmentation mechanisms contributing to the H+ + C+ + CH+ channel. Newton diagrams and Dalitz plots are used to trace these fragmentation mechanisms. It is found that both concerted fragmentation and sequential pathways involving CH bond breaking prior to CC contribute to this channel. The possible electronic states of the C2H23+ precursor that contribute to the identified fragmentation mechanisms are analyzed using quantum chemical calculations. Furthermore, the influence of collision dynamics between the projectile and target on the dissociation mechanisms is discussed by comparing the contributions from the T1I2 channel and the reversed T2I1 channel, where one electron is transferred while ionizing the other two. The T2I1 channel is observed to be more efficient in initiating fragmentation mechanisms with higher kinetic energy release.
Article
Chemistry, Multidisciplinary
Chao Wang, Yuzhuo Chen, Daijian Su, Wai-Lun Man, Kai-Chung Lau, Lianhuan Han, Liubin Zhao, Dongping Zhan, Xunjin Zhu
Summary: The new electrocatalyst EP-CoP shows improved efficiency and durability in CO2 reduction reactions by enhancing the dispersion of CoN4 sites and optimizing redox kinetics. In commercial flow cells, EP-CoP demonstrates excellent catalytic performance under various overpotential conditions.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Huatian Shi, Lin Cheng, Yi Pan, Chi-Keung Mak, Kai-Chung Lau, Tai-Chu Lau
Summary: This work investigates the effects of weak acid (such as CH3CO2H) and weak Lewis acid (such as Ca2+) on C-H bond activation by KMnO4. The results show that efficient oxidation of cyclohexane can be achieved in the presence of AcOH and Ca2+. DFT calculations reveal the hydrogen bonding and coordination between MnO4-, AcOH, and Ca2+. These activating effects may also apply to other metal-oxo species.
Article
Chemistry, Multidisciplinary
Chang Shen, Wasihun Menberu Dagnaw, Ching Wai Fong, Kai Chung Lau, Cheuk-Fai Chow
Summary: The oxidative catalytic halogenations of the C(sp(3))-H bond of alkanes promoted by Fe-III(acacen)Cl and Fe-III(acacen)Br in the presence of trifluoroacetic acid were investigated, involving four major steps with trifluoroacetic acid playing a key role in forming the high-valent iron-oxo intermediate and generating reaction selectivity.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Jing Xiang, Jiang Zhu, Miaomiao Zhou, Lu-Lu Liu, Li-Xin Wang, Min Peng, Bi-Shun Hou, Shek-Man Yiu, Wai-Pong To, Chi-Ming Che, Kai-Chung Lau, Tai-Chu Lau
Summary: The photoreactions of a luminescent osmium(VI) nitrido complex, [Os-VI (N)(L)(CN)(3)](-) (OsN, HL = 2-(2-hydroxy-5-nitrophenyl)benzoxazole), with catechol (H(2)Cat) and hydroquinone (H(2)Q) result in the cleavage of strong C-OH bonds in dihydroxybenzenes and the conversion of coordinated cyanide to carbon monoxide.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Inorganic & Nuclear
Yunling Pan, Lin Cheng, Yi Pan, Wai-Lun Man, Shek-Man Yiu, Jianhui Xie, Kai-Chung Lau, Tai-Chu Lau
Summary: This study reports the first example of oxidative cleavage of primary amines by a ruthenium(VI) nitrido complex. The reaction is driven by the formation of stable NuN after the initial coupling of the amine N and the nitrido ligand.
DALTON TRANSACTIONS
(2022)
Article
Chemistry, Multidisciplinary
Jing Xiang, Min Peng, Yi Pan, Li-Juan Luo, Shun-Cheung Cheng, Xin-Xin Jin, Shek-Man Yiu, Wai-Lun Man, Chi-Chiu Ko, Kai-Chung Lau, Tai-Chu Lau
Summary: The study presented the first example of N-dealkylation of various alkylamines by a luminescent osmium(VI) nitrido complex induced by visible light.