Reaction of AgBr with TabHPF6 (TabH = 4-(trimethylammonio)benzenethiol) readily produces a unique one-dimensional coordination polymer [(TabH)(AgBr2)]n (1), consisting of anionic chains [AgBr2]n(n-) with hydrogen bonds to TabH(+) cations. By examining its electrical resistance and stability upon exposure to ammonia and seven common organic amines in water under ambient conditions, compound 1 is found to exhibit good stability and reproducibly high sensitivity toward these analytes at low concentrations. Especially, it can selectively detect NH3 in water with the detection limit as low as 0.05 ppm. This chemiresistive sensing system has the potential for highly efficient monitoring of ammonia and amines responsible for water pollution, eutrophication, food contamination, and industrial hazards.
The integration of a geometrically rigid Pd(ii), a coordinatively monotonous N-heterocyclic carbene 1,3-dimethylimidazoline-2-ylidene (IMe), and a flexible zwitterionic thiolate 4-(trimethylammonio)benzenethiolate (Tab) affords a class of Pd-IMe-Tab complexes with various nuclearities, namely, trans-[Pd(IMe)(Tab)](OTf) (2, mononuclear), cis-[Pd(IMe)(Tab)](OTf)(Cl) (3a, mononuclear), cis-[Pd(IMe)(Tab)](PF)·MeCN (3b·MeCN, mononuclear), [Pd(IMe)(Tab)](PF)·2MeCN (4·2MeCN, dinuclear) and [Pd(IMe)(Tab)](OTf)(Cl) (5, tetranuclear). Further presence of Ag(i) in the assembly provides a heterometallic octanuclear cluster of [PdAg(IMe)(Tab)](PF) (6). Compounds 2-6 are formed by the reaction of trans-Pd(IMe)Cl (1) with various additional reagents via different reaction pathways. These compounds are characterized by means of FT-IR, H andC NMR, ESI-MS, elemental analysis and X-ray crystallography. Notably, the skeleton of compound 5 features a [PdS] parallelogram wherein each of the four Pd(ii) centers bisects the edge defined by the S atoms. The main skeleton of compound 6 is an oval-shaped PdAgS unit, featuring an edge-fused norbornane-like (PdAgS) framework appended by two additional PdS motifs at the polar positions. Compounds 5 and 6 also feature PdPd (5), PdAg and AgAg (6) interactions. Compound 5 as a representative example is highly effective at catalyzing Suzuki-Miyaura couplings in water, highlighting the potential of applying these types of homo- and heterometallic clusters as catalysts for organic transformations in environmentally benign media.
We herein report the preparation of unique heteroatom-doped and carbon-based AuAg alloy nanoparticles (NPs) via the pyrolysis of a structurally defined octanuclear heterometallic Au(i)-Ag(i) cluster [Au4Ag4(Dppy)4(Tab)4(MeCN)4](PF6)8 (2, Dppy = diphenylphosphine-2-pyridine and Tab = 4-(trimethylammonio)benzenethiolate). This cluster-precursor approach exerts a fine control over the spatial arrangement, size and uniformity of the AuAg alloy NPs as well as the doped heteroatoms (P, N, F and S). The optimized material prepared at 450 °C efficiently catalyzes the oxidative coupling of anilines to yield azobenzenes under mild conditions.
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