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Li, Xingqi; Chu, Dongdong; Qiu, Haotian; Wu, Yabo; Hou, Xueling
doi: 10.1039/d3dt00401epmid: 36919645
Borate has become a hot topic because of its rich structural chemistry and excellent properties for functional materials fields. The rearrangement of π-conjugated B–O units is key to enhancing the optical anisotropy, but it remains a challenge. Herein, by introducing [AlO4] tetrahedra, a new congruent melting aluminoborate LiCs3AlB7O14 with [B7O14] clusters was discovered. This work confirms that the introduction of [AlO4] tetrahedra can lead to the rearrangement of anionic framework of the borate system and thereby enhance the birefringence of LiCs3AlB7O14. The birefringence is about 4.1 times higher than that of its congener Li4Cs3B7O14 with the same [B7O14] clusters. Similarly, the effects of [AlO4] tetrahedra on the rearrangement of the B–O anionic framework are also demonstrated in other known borates.
Shiga, Takuya; Miyamoto, Haruka; Okamoto, Yukiko; Oshio, Hiroki; Mihara, Nozomi; Nihei, Masayuki
doi: 10.1039/d2dt03892gpmid: 36779535
A series of tetranuclear [Cu3Ln] complexes, [Cu3Gd(L)3(NO3)2(H2O)3](NO3)·H2O (1), [Cu3Tb(L)3(NO3)2(H2O)3](NO3) (2) and [Cu3Dy(L)3(NO3)3(H2O)2]·1.5(H2O) (3), were synthesized by a one-pot reaction using a simple tetraketone-type ligand (H2L = (3Z,5Z)-4,5-dihydroxy-3,5-octadiene-2,7-dione). X-ray structural analyses revealed that each complex has a planar tetranuclear core of [Cu3Ln] (Ln = Gd, Tb, and Dy), in which the Ln ion is accommodated in the centre of a Cu3O6 metallocycle. A cryomagnetic study revealed that all complexes show intramolecular ferromagnetic interactions between Cu(ii) and Ln(iii) ions. The [Cu3Gd] complex (1) has an ST = 5 spin ground state and shows a magneto-caloric effect with a maximum magnetic entropy change (–ΔSm) of 16.4 J kg−1 K−1 (5 T, 2.4 K). On the other hand, the [Cu3Tb] complex (2) shows a slow magnetic relaxation behavior under a zero magnetic field. The analysis of an Arrhenius plot reveals that the effective energy barrier of spin reversal is 13.1 K. The [Cu3Dy] complex (3) also shows a slow magnetic relaxation under 1300 Oe dc magnetic field with an effective energy barrier of 6.82 K.
Bellavita, Rosa; Leone, Linda; Maione, Angela; Falcigno, Lucia; D'Auria, Gabriella; Merlino, Francesco; Grieco, Paolo; Nastri, Flavia; Galdiero, Emilia; Lombardi, Angela; Galdiero, Stefania; Falanga, Annarita
doi: 10.1039/d2dt04099apmid: 36744636
Ferric iron is an essential nutrient for bacterial growth. Pathogenic bacteria synthesize iron-chelating entities known as siderophores to sequestrate ferric iron from host organisms in order to colonize and replicate. The development of antimicrobial peptides (AMPs) conjugated to iron chelators represents a promising strategy for reducing the iron availability, inducing bacterial death, and enhancing simultaneously the efficacy of AMPs. Here we designed, synthesized, and characterized three hydroxamate-based peptides Pep-cyc1, Pep-cyc2, and Pep-cyc3, derived from a cyclic temporin L peptide (Pep-cyc) developed previously by some of us. The Fe3+ complex formation of each ligand was characterized by UV-visible spectroscopy, mass spectrometry, and IR and NMR spectroscopies. In addition, the effect of Fe3+ on the stabilization of the α-helix conformation of hydroxamate-based peptides and the cotton effect were examined by CD spectroscopy. Moreover, the antimicrobial results obtained in vitro on some Gram-negative strains (K. pneumoniae and E. coli) showed the ability of each peptide to chelate efficaciously Fe3+ obtaining a reduction of MIC values in comparison to their parent peptide Pep-cyc. Our results demonstrated that siderophore conjugation could increase the efficacy and selectivity of AMPs used for the treatment of infectious diseases caused by Gram-negative pathogens.
Lu, Zhou; Vanga, Mukundam; Li, Shan; Adebanjo, Joseph O.; Patterson, Monika R.; Dias, H. V. Rasika; Omary, Mohammad A.
doi: 10.1039/d2dt03725dpmid: 36594647
Described herein are the synthesis, structure, and photophysics of the iodo-substituted cyclic trinuclear copper(i) complex, Cu3[4-I-3,5-(CF3)2Pz]3 supported by a highly-fluorinated pyrazolate in comparison with its previously reported 4-Br/4-Cl analogues. The crystal structure is stabilised by multiple supramolecular interactions of Cu3⋯I and hydrogen/halogen bonding. The photophysical properties and supramolecular interactions are investigated experimentally/computationally for all three 4-halo complexes vis-à-vis relativistic effects.
Qiao, Xianji; Qiu, Yi; Xin, Junjie; Chen, Da; Ma, Zili; Corkett, Alex J.; Cai, Guohong; Cai, Guanqun; Qu, Shangqing; Wang, YuChao; Zhu, Zhenyu; Gao, Yiman; Wang, Zhigang; Dronskowski, Richard; Li, Guobao; Sun, Junliang
Wang, Xun; Fang, Zixuan; Hu, Xin; Fu, Bowen; Feng, Tingting; Li, Teng; Wu, Mengqiang
doi: 10.1039/d3dt00112apmid: 36883845
Structural instability at high voltage severely restricts the reversible capacity of the LiCoO2 cathode. Moreover, the main difficulties in achieving high-rate performance of LiCoO2 are the long Li+ diffusion distance and slow Li+ intercalation/extraction during the cycle. Thus, we designed a modification strategy of nanosizing and tri-element co-doping to synergistically enhance the electrochemical performance of LiCoO2 at high voltage (4.6 V). Mg, Al, and Ti co-doping maintains the structural stability and phase transition reversibility, which promotes the cycling performance of LiCoO2. After 100 cycles at 1 C, the capacity retention of the modified LiCoO2 reached 94.3%. In addition, the tri-elemental co-doping increases Li+ interlayer spacing and enhances Li+ diffusivity by tens of times. Simultaneously, nanosize modification decreases Li+ diffusion distance, leading to a significantly enhanced rate capacity of 132 mA h g−1 at 10 C, much better than that of the unmodified LiCoO2 (2 mA h g−1). After 600 cycles at 5 C, the specific capacity remains at 135 mA h g−1 with a capacity retention of 91%. The nanosizing co-doping strategy synchronously enhanced the rate capability and cycling performance of LiCoO2.
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Perovskite nanomaterials have been highly thought as next-generation light emitters after recent development owing to their benefits of simple synthesis, low-cost, large-area, and wide color gamut. Encouragingly, the external quantum efficiencies (EQEs) of green, red, and near-infrared perovskite light-emitting diodes (PeLEDs) have exceeded more than 20%. However, the performance of the blue PeLEDs is still lower than other analogs, which severely limits the applications of PeLEDs in future full-color displays. Herein, we have reviewed the advances in blue perovskite NCs and their applications in blue PeLEDs. Promising blue perovskite emitters and strategies for fabricating highly efficient blue PeLEDs based on perovskite NCs are investigated and highlighted. Moreover, we point out the main challenges in blue perovskite NC LEDs including low electroluminescence efficiency (EL), spectral instability, the difficulty of charge injection, and device optimization. The perspectives for the further development of blue PeLEDs are also presented.
doi: 10.1039/d3dt00384apmid: 36880672
We describe the synthesis, crystal structure and semiconducting properties of a number of hexacyanidometallates with the formula A2[MFe(CN)6]·xH2O (A = Na, K; M = Mg, Ca, Sr and Ba). All crystal structures were studied via single-crystal or powder X-ray diffraction. The unexpectedly low-symmetric structures in these ferrocyanides are described and contrasted with analogous transition-metal compounds which have been reported to be strictly or nearly cubic. The amount of crystal water in the structure for powder samples was determined by the thermogravimetric analysis (TGA), supported by IR and Raman spectroscopy. Electronic-structure calculations of K2[MgFe(CN)6] and K2[CaFe(CN)6] are compared with experimental UV-Vis measurements. The large band gaps by advanced theory indicate that the smaller experimental band gaps are due to surface effects of impurity states. Mott–Schottky curves of K2[MgFe(CN)6], K2[CaFe(CN)6] and K2[BaFe(CN)6]·3H2O exhibit positive slopes, which characterizes these compounds as n-type semiconductors.