Nitrile functionalized silver(I) N-heterocyclic carbene complexes: DFT calculations and antitumor studies

A Comprehensive Study of N-Butyl-1H-Benzimidazole

Imidazole derivatives have found wide application in organic and medicinal chemistry. In particular, benzimidazoles have proven biological activity as antiviral, antimicrobial, and antitumor agents. In this work, we experimentally and theoretically investigated N-Butyl-1H-benzimidazole. It has been shown that the presence of a butyl substituent in the N position does not significantly affect the conjugation and structural organization of benzimidazole. The optimized molecular parameters were performed by the DFT/B3LYP method with 6-311++G(d,p) basis set. This level of theory shows excellent concurrence with the experimental data. The non-covalent interactions that existed within our compound N-Butyl-1H-benzimidazole were also analyzed by the AIM, RDG, ELF, and LOL topological methods. The color shades of the ELF and LOL maps confirm the presence of bonding and non-bonding electrons in N-Butyl-1H-benzimidazole. From DFT calculations, various methods such as molecular electrostatic potential (MEP), Fukui functions, Mulliken atomic charges, and frontier molecular orbital (HOMO-LUMO) were characterized. Furthermore, UV-Vis absorption and natural bond orbital (NBO) analysis were calculated. It is shown that the experimental and theoretical spectra of N-Butyl-1H-benzimidazole have a peak at 248 nm; in addition, the experimental spectrum has a peak near 295 nm. The NBO method shows that the delocalization of the aσ-electron from σ (C1-C2) is distributed into antibonding σ* (C1-C6), σ* (C1-N26), and σ* (C6-H11), which leads to stabilization energies of 4.63, 0.86, and 2.42 KJ/mol, respectively. Spectroscopic investigations of N-Butyl-1H-benzimidazole were carried out experimentally and theoretically to find FTIR vibrational spectra.

Preparation of Large Conjugated Polybenzimidazole Fluorescent Materials and Their Application in Metal Ion Detection

A new type of conjugated polybenzimidazole (CPBI) was synthesized through a simple polycondensation reaction without metal catalysis, and N-alkylation modification was carried out to solve the problems of solubility and fluorescence properties. A series of nano-microsphere polymers CPBI_n with large conjugation, good solubility, and strong fluorescence has been successfully used as “turn-off” fluorescent probes for the first time. The results show that, under suitable N-alkylation conditions, the obtained CPBI_n can be used as a highly sensitive and selective fluorescent probe for the detection of Cu²⁺ and Zn²⁺ at the same time, and their detection limits are both nM levels. In addition, CPBI₂ can be designed as an ultra-sensitive IMPLICATION logic gate at the molecular level, cyclically detecting Cu²⁺. With the test paper containing CPBI₂, easy and quick on-site detection can be achieved. This research provides a new idea for the brief synthesis of multifunctional materials.

Coinage Metal N-Heterocyclic Carbene Complexes: Recent Synthetic Strategies and Medicinal Applications

New weapons are constantly needed in the fight against cancer. The discovery of cisplatin as an anticancer drug prompted the search for new metal complexes. The successful history of cisplatin motivated chemists to develop a plethora of metal-based molecules. Among them, metal-N-heterocyclic carbene (NHC) complexes have gained significant attention because of their suitable qualities for efficient drug design. The enhanced applications of coinage metal-NHC complexes have encouraged a gradually increasing number of studies in the fields of medicinal chemistry that benefit from the fascinating chemical properties of these complexes. This review aims to present recent developments in synthetic strategies and medicinal applications of copper, silver and gold complexes supported by NHC ligands.

N-heterocyclic carbene-metal complexes as bio-organometallic antimicrobial and anticancer drugs, an update (2015–2020)

N-heterocyclic carbenes (NHCs) are organic compounds that typically mimic the chemical properties of phosphines. NHCs have made a significant impact on the field of coordination and organometallic chemistry because they are easy to prepare and handle and because of their versatility and stability. Importantly, the physicochemical properties of NHCs can be easily fine-tuned by simple variation of substituents on the nitrogen atoms. Over the past few years, various NHC–metal complexes have been extensively used as metal-based drug candidates and catalysts (homogeneous or heterogeneous) for various applications. To help assist future work with these compounds, this review provides a thorough review on the latest information involving some biomedical applications of NHC–metal complexes. Specifically, this article focuses on recent advances in the design, synthesis, characterization and biomedical applications (e.g., antimicrobial and anticancer activity) of various NHC–metal complexes (metal: silver, gold, palladium, rhodium, ruthenium, iridium and platinum) covering work published from 2015 to 2020. It is hoped that the promising discoveries to date will help accelerate studies on the encouraging potential of NHC–metal complexes as a class of effective therapeutic agents.

Biological Activities of NHC–Pd(II) Complexes Based on Benzimidazolylidene N-heterocyclic Carbene (NHC) Ligands Bearing Aryl Substituents

N-heterocyclic carbene (NHC) precursors (2a–i), their pyridine-enhanced precatalyst preparation stabilization and initiation (PEPPSI)-themed palladium N-heterocyclic carbene complexes (3a–i) and palladium N-heterocyclic triphenylphosphines complexes (4a–i) were synthesized and characterized by elemental analysis and 1H NMR, 13C NMR, IR, and LC–MS spectroscopic techniques. The (NHC)Pd(II) complexes 3–4 were tested against MCF7 and MDA-MB-231 cancer cells, Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), Candida albicans microorganisms, Leishmania major promastigotes and amastigotes, Toxoplasma gondii parasites, and Vero cells in vitro. The biological assays indicated that all compounds are highly active against cancer cells, with an IC50 < 1.5 µg mL−1. Eight compounds proved antibacterial and antileishmanial activities, while only three compounds had strong antifungal activities against C. albicans. In our conclusion, compounds 3 (b, f, g, and h) and 4b are the most suitable drug candidates for anticancer, antimicrobial, and antiparasitical.

Light-stable polypyridine silver(i) complexes of 1,3,5-triaza-7-phosphaadamantane (PTA) and 1,3,5-triaza-7-phosphaadamantane-7-sulfide (PTA[double bond, length as m-dash]S): significant antiproliferative activity of representative examples in aqueous media

A series of novel silver(i) 2,2':6',2''-terpyridine (tpy), 4'-(4-methylphenyl)-2,2':6':2''-terpyridine (tpy-Ph-Me) and 1,10-phenanthroline-5,6-dione (dione) derivatives containing PTA (1,3,5-triaza-7-phosphaadamantane) or 1,3,5-triaza-7-phosphaadamantane-7-sulfide (PTA[double bond, length as m-dash]S) have been synthesized and fully characterized. Two types of complexes have been obtained, monocationic [Ag(tpy)(PTA)](NO₃) (1), [Ag(tpy-Ph-Me)(PTA)](NO₃) (2), [Ag(dione)(PTA[double bond, length as m-dash]S)](BF₄) (4) and [Ag(dione)₂](PF₆) (5) and neutral [Ag(dione)(PTA[double bond, length as m-dash]S)(NO₃)] (3). The solid-state structures of four complexes have been determined by single-crystal X-ray diffraction. Complexes 1 and 2 are luminescent at room temperature and 77 K while 5 shows emission only at 77 K. Compounds 3 and 4 are not emissive. Furthermore, representative light-stable and water-soluble 1 and 3 were evaluated for their cytotoxic activities on the normal human dermal fibroblast (NHDF) cell line and their antitumor activity using the human lung carcinoma (A549), epithelioid cervix carcinoma (HeLa) and human breast adenocarcinoma (MCF-7) cell lines. Interactions between the complexes and human serum albumin (HSA) using UV-Vis, fluorescence and circular dichroism spectroscopy (CD) were also investigated.

R. S, Patil SA, Małecki JG, Budagumpi S. Coumarin-substituted 1,2,4-triazole-derived silver(i) and gold(i) complexes: synthesis, characterization and anticancer studies

A series of coumarin-substituted 1,2,4-triazolium salts and their respective silver– and gold– N-heterocyclic carbene complexes have been reported. The complexes displayed promising anticancer activity with GI₅₀ values of up to 0.354 μM and 8.5983 μM against MCF 7 and HT-29 cell lines, respectively.