Dalton Transactions

doi: 10.1039/C9DT90201Epmid: 31528946

doi: 10.1039/c9dt90201epmid: 31528946

doi: 10.1039/C9DT90202Cpmid: 31528947

doi: 10.1039/c9dt90202cpmid: 31528947

Fernandes, Diana M.; Peixoto, Andreia F.; Freire, Cristina

doi: 10.1039/c9dt01691kpmid: 31407753

Carbon dioxide (CO2) is regarded as the main contributor to the greenhouse effect. As a potential strategy to mitigate its negative impacts, the reduction of CO2 is environmentally critical, economically meaningful and scientifically challenging. Concerns regarding anthropogenic emissions have recently sparked interest in the CO2 chemical transformation techniques. Being both thermodynamically and kinetically unfavorable, CO2 conversion generally requires efficient metal-based catalysts although they have multiple competitive disadvantages such as high costs, low availability and detrimental effects on the environment. A new class of catalysts based on earth-abundant carbon materials has been considered as an efficient, low-cost, metal-free alternative for both the capture and catalytic or electrocatalytic conversion of CO2. CO2 electrochemical reduction (CO2RR) offers a new and important pathway towards renewable energy storage and production of fuels, and CO2 cycloaddition with epoxides to cyclic or polymeric carbonates opens up new prospects for the production of polymers and fine chemicals. This review provides an overview of the progresses made in nitrogen-doped metal-free carbon catalysts for CO2 electrochemical conversion and CO2 conversion into cyclic carbonates into useful fuels and chemicals with a focus on the results underlying their mechanistic behavior, advantages and/or limitations of this metal-free N-doped carbon catalysts on CO2 conversion and valorisation.

Wu, Qi; Liu, Xian; Liang, Fei; Xu, Siran; Pi, Hongbing; Han, Xue; Liu, Yang; Lin, Zheshuai; Li, Yanjun

doi: 10.1039/c9dt02949dpmid: 31451814

This study reports, for the first time, the second-harmonic generation (SHG) property of Pb7F12Cl2 as a promising infrared nonlinear optical (NLO) material. Powder second-harmonic generation (SHG) indicates that the compound exhibits phase-matchable SHG properties, which are 1.6 times stronger than those of KH2PO4 (KDP). The infrared transmission range could reach 20 μm. The UV absorption indicated that the band gap was about 4.5 eV. A preliminary measurement of laser damage threshold (LDT) is about 80 MW cm−2, which is much higher than AgGaS2 (currently commercialized IR NLO material, 5.2 MW cm−2, measured in the same condition), indicating that Pb7F12Cl2 is a potential IR NLO material with high LDT. Theoretical calculations were also performed to elucidate its band structure, electronic configuration and second-order nonlinear coefficients. Particularly, the distinct role of different Pb atoms located in divergent coordinations has also been elaborated using orbital analysis.

Dayanidhi, David Paul Elisa; Malapati, Rozaria Pinky; Vaidyanathan Ganesan, Vaidyanathan

doi: 10.1039/c9dt01225gpmid: 31455966

Selective detection of DNA defects is an attractive approach for early detection of various tumors and diseases. Ru(ii), Rh(iii) and hybrid complexes have been reported in this regard. Here, we present three heteroleptic cyclometalated Ir(iii) complexes [Ir(phpy)2(imiphen)]+(Ir-1), [Ir(phpy)2(furphen)]+(Ir-2) and [Ir(phpy)2(faqphen)]+(Ir-3) where imiphen: 2-(1H-imidazol-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline; furphen: 2-(furan-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline and faqphen: 2-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione have been synthesized and characterized by analytical techniques. All three complexes recognize DNA defects with high selectivity as Ir-1 recognizes the abasic site opposite T and CA mismatch, Ir-2 recognizes Ab : G and Ir-3 recognizes the TT mismatch preferably. The results from this study further emphasize that the development of new luminescent probes requires fine-tuning of the ligand structure and the choice of the metal center to improve selectivity in recognition of DNA defects.

Ma, Hui-Yan; Zhang, Yong-Zheng; Yan, Hui; Zhang, Wen-Jie; Li, Yun-Wu; Wang, Su-Na; Li, Da-Cheng; Dou, Jian-Min; Li, Jian-Rong

doi: 10.1039/c9dt02694kpmid: 31469147

Simultaneously involving abundant [NH2(CH3)2]+ cations and uncoordinated carboxylate oxygen atoms as dual active sites, two microporous CoII-MOFs (LCU-105 and LCU-106, LCU = Liaocheng University) both exhibit highly selective adsorption of CO2/CH4 and CO2/N2. GCMC theoretical simulations provide good verification of the experimental results.

Connah, Liam; Truffault, Vincent; Platas-Iglesias, Carlos; Angelovski, Goran

doi: 10.1039/c9dt02672jpmid: 31361286

Understanding the relationship between chemical structure and the effectiveness of bioresponsive magnetic resonance imaging (MRI) contrast agents can offer help to identify key components required for the future development of such probes. Here, we report the development and characterisation of two novel monomeric bifunctional chelators, L1 and L2, whose paramagnetic metal complexes can serve as calcium-responsive contrast agents. Specifically, relaxometric titrations, luminescence lifetime measurements, high resolution NMR and diffusion experiments, as well as density functional theory (DFT) calculations were carried out to assess the behaviour of each system. Minor structural differences between the probes resulted from the extension of the linker between the macrocyclic lanthanide chelator and the acyclic Ca-binding moiety. Relaxometric titrations of both systems, GdL1 and GdL2, showed an increase in r1 and r2 relaxivity upon Ca2+ addition, with the derivative bearing the longer linker showing a greater overall change. The hydration states of the europium analogues were assessed revealing a higher initial hydration state for EuL2. Diffusion ordered NMR spectroscopy revealed negligible changes in the diffusive properties of both systems upon the addition of Ca2+, while NMR studies of the Y3+, Yb3+ and Eu3+ analogues provided further insights into the structural behaviour of the linker unit in both the unsaturated and Ca-saturated states. DFT calculations supported the different coordination modes of the studied paramagnetic complexes in the presence and absence of Ca2+. Overall, our findings demonstrate the impact of subtle changes to the structure of such probes, affecting a range of properties and their coordination behaviour.

Ahmadijokani, Farhad; Ahmadipouya, Salman; Molavi, Hossein; Arjmand, Mohammad

doi: 10.1039/c9dt02328cpmid: 31353374

Mixed-matrix membranes (MMMs) are promising candidates for carbon dioxide separation. However, their application is limited due to improper dispersion of fillers within the polymer matrix, poor interaction of fillers with polymer chains, and formation of defects and micro-voids at the interface of both phases, which all result in the decline of the gas separation performance of MMMs. In this work, we present a new method to overcome these challenges. To this end, a series of MMMs based on polyethersulfone (PES) as the continuous polymer matrix and MIL-53-derived MOFs as the dispersed filler were prepared. FTIR-ATR, XRD, TGA, FESEM, and N2 adsorption/desorption analyses were employed to characterize the structural properties of the synthesized nanoparticles. The obtained results indicated that 3-aminopropyltriethoxysilane (APTES) molecules were successfully attached onto the surface of NH2-MIL-53(Al). Morphological characterization by FESEM and energy dispersive X-ray mapping (EDX) showed that desirable distribution within the whole membrane thickness, suitable nanoscale dispersion, and excellent interface were achieved by using amino-silane-grafted NH2-MIL-53(Al) (A-MIL-53(Al)) nanoparticles. The permeation results indicated that the permeability of two gases and the ideal CO2/CH4 selectivity enhanced by increasing the concentration of MOFs. In particular, comparing the experimental gas separation results of A-MMM-10 with those of pure PES membrane showed an 84% increase in the CO2 permeability and a 70% increase in CO2/CH4 selectivity. These results suggest that post-synthetic modification of MOF nanoparticles and strong interfacial adhesion between functionalized nanoparticles and polymer matrix could be a useful method to eliminate interfacial voids and improve gas separation efficiency.