Unusual complexation of Cu(I) by pyrimidine/pyridine-pyrazole derived ligands exploiting the molecular function of 2-mercapto-4,6-dimethylpyrimidine – Syntheses, crystal structures and electrochemistry

Unraveling the Origin of an Unusual Shift in the Electroluminescence of 1D CsCu2I3 Light-Emitting Diodes

Lead-free low-dimensional copper-based metal halides are promising luminescent materials for broadband LEDs owing to their broad self-trapped exciton (STE) emission. However, recently, in 1D CsCu2I3, a discrepancy between their electroluminescence (EL) and photoluminescence (PL) has been observed. As a result, the overall output color from LEDs is significantly different than the anticipated emission. To unveil the origin of this discrepancy, here, we provide comprehensive analyses and show that the shift in the EL is caused neither by any structural/optical interactions between CsCu2I3 and electron transport layers (ETL) nor by the degradation of 1D CsCu2I3. Instead, it depends on the carrier imbalance on CsCu2I3, mainly due to the difference in the electron mobility of the ETLs and the electron density on the CsCu2I3 layer. By varying the ETLs, different colored 1D CsCu2I3 LEDs with peaks at 556, 590, and 647 nm are fabricated, and a maximum luminance of over 2000 cd/m2 is achieved for a 556 nm LED. Further, by limiting the electron mobility and injection to 1D CsCu2I3 using an insulating LiF layer at the CsCu2I3/ETL interface, more red-shifted LEDs are achieved confirming the critical role of electron density on the EL characteristics of 1D CsCu2I3.

Two 6/10-connected Cu12S6 cluster-based organic frameworks: crystal structure and proton conduction

Nowadays, although the exploration of proton conductive materials has ranged from traditional sulfonated polymers to novel crystalline solid materials such as MOFs, COFs, and HOFs, research on crystalline cluster-based organic framework materials is very limited. Here, a pair of homologues Cu(i)-based organic framework containing a Cu12S6 cluster, [Cu12(MES)6(H2O)3]n (1) and {[Cu12(MPS)6(H2O)4]·6H2O}n (2) (H2MES = 2-mercaptoethanesulfonate acid and H2MPS = 2-mercaptoethanesulfonate acid), were hydrothermally synthesized under the same conditions and fully investigated for their proton conduction. Their structures were characterized by means of single-crystal X-ray diffraction, elemental analysis, thermogravimetric analyses, and PXRD measurements. The two MOFs show significant structural differences in the topological fashions. MOF 1 has a three-dimensional network and can be simplified into two topology types: a 10-connected gpu structure with a Schläfli symbol (312·426·57) and a 3,12-connected new topology with a point symbol {3·42}2{310·418·519·614·74·9}. MOF 2 also has a three-dimensional framework and topology as a 6-connected pcu primitive cubic network with a Schläfli symbol {412·63}. The two MOFs show different proton conduction parameters, but both indicate temperature-dependent proton conductive features. Intriguingly, the two MOFs exhibit high water stability and their proton conductivities are 3.63 × 10-5 and 2.75 × 10-5 S cm-1 under 333 K and 98% RH, respectively. The suggested mechanism for the synthesis for 1 and 2, and their proton conductivity performance comparison has been discussed in detail. In addition, Hirshfeld surface and fingerprint analysis on the two MOFs were computed to compare contacts between the molecules, which is essential for analyzing the relationships between their hydrogen bonds and proton conductivity properties.

Structural Diversity of Copper(I) Cluster-Based Coordination Polymers with Pyrazine-2-thiol Ligand

Six novel copper(I) cluster-based coordination polymers (CPs) [Cu₉(pzt)₇Cl₂]_n (1), [Cu₂(pzt)Cl]_n (2), [Cu₄(pzt)₃Br]_n (3), [Cu(pzt)]_n (4), [Cu₄(pzt)₃I]_n (5), and [Cu₇(pzt)₆I]_n (6) were solvothermally synthesized using Hpzt (Hpzt = pyrazine-2-thiol) ligand and well-characterized by elemental analysis, infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD). Six CPs exhibit either 2D (4 and 6) or 3D (1-3, and 5) network based on diverse multinuclear {Cu_xS_y} clusters. The structural evolutions of 1-6 are greatly influenced by types of metal halides and the ligand-to-metal molar ratio used in the reaction. Among them, compound 1 displays interesting temperature-dependent photoluminescence arising from triplet cluster-centered (³CC) excited state from the cluster metal core. Compounds 1-6 also exhibit photocurrent responses upon visible-light illumination (λ = 420 nm) in the order 6 > 5 > 3 > 1 > 4 > 2. This work not only shows the structural diversity of {Cu_xS_y} clusters-based CPs but also provides an interesting insight into structural modulation using crystal engineering concept.

Precursor-driven selective synthesis of hexagonal chalcocite (Cu2S) nanocrystals: structural, optical, electrical and photocatalytic properties

A new single-source precursor, [Cu(mdpa)₂][CuCl₂], is used to prepare selectively high chalcocite (Cu₂S) with excellent photodegradation of Congo red (CR).

Synthesis, Characterisation and Antimicrobial Activity 1-Aminopyrimidine-2(1H)-Thione and its Co(II), Ni(II), Pd(II) and Pt(II) Complexes

Metal complexes of 1-aminopyrimidine-2(1H)-thione were prepared from acetate salts of Co(II), Ni(II), Pd(II) and Pt(II) in methanol. Electronic spectral data and magnetic moment measurements suggest mononuclear square planar geometrical structures for the metal complexes. The ligand and all the metal complexes were evaluated for their antimicrobial activity. The newly synthesised ligand and the Co(II) complex showed moderate activity against all tested bacteria and yeast strains.