Nickel complexes bearing quinoline derived NNS donor ligands as catalytic activators for N-alkylation of anilines with alcohols.

Herein, we have reported a new series of NNS-donor ligands coordinated Ni(II) complexes and utilized them as catalytic activator to synthesize N-alkylated aminesand 1,2-disubstituted benzimidazoles. The separate reaction of  [C9H6N-NH-C(O)-CH2-S-Ar] [Ar = C6H5 (L1); C6H4Cl-4 (L2);C6H4Me-4 (L3) and C6H4-OMe-4 (L4)] with Ni(OAc)2 in methanol at 80°C for 3 hours resulted in octahedral nickel complexes [(L1-H)2Ni] (C1), [(L2-H)2Ni] (C2), [(L3-H)2Ni] (C3), and [(L4-H)2Ni] (C4), respectively. All compounds have been characterized by micro and spectroscopic analysis. The molecular structure of complexes C1-C3 has also been determined by single crystal X-ray diffraction data. The utility of complexes C1-C4 were evaluated for the N-alkylation of aniline with benzyl alcohols, and for 1,2-disubstituted benzimidazoles synthesis. The obtained results indicate that complex C1 showed better catalytic activity in both N-alkylation of amines with benzyl alcohols [catalyst loading: 2.0 mol%; Yield up to 92%], and for 1,2-disubstituted benzimidazoles derivatives [catalyst loading: 2.0 mol%; Yield up to 94%)]. The mechanistic studies suggested that the reaction works through hydrogen borrowing from benzyl alcohol and its subsequent utilization for in situ reduction of imine. The experimentally observed catalytic reactivity patterns of complexes C1-C4 have found in good agreement with the HOMO-LUMO energy gaps obtained by DFT analysis of corresponding complexes.

Postlaryngectomy pharyngoplasty with melolabial flap.

To the best of our knowledge, this is the largest case series describing the use of a melolabial flap for postlaryngectomy pharyngoplasty. It is an excellent alternative for pharyngoplasty, especially in cases post chemoradiotherapy. It accomplishes the goal while removing the restrictions of local and distant flaps. Although donor site morbidity is acceptable, specific consent is required due to the possibility of functional and cosmetic impairment. Additional cases with a larger sample size and a longer follow-up period can assist corroborate our first findings. In addition, because we tend to protect facial vessels for this flap, a follow-up about the compromise of oncological safety at level IB is required. In our case series, however, there was no recurrence until the final follow-up. As a result, it is a better option to pharyngoplasty post laryngectomy.

Pd(II) complexes bearing NNS pincer ligands: unveiling potent cytotoxicity against breast and pancreatic cancer.

The continuously increasing rate of breast cancer is one of the major threats to female health worldwide. Recently, palladium complexes have emerged as impressive candidates with effective biocompatibility and anticancer activities. Hence, in the present study, we report a new series of palladium complexes bearing NNS pincer ligands for cytotoxicity studies. The reaction of thiophenol/4-chlorothiophenol/4-methylthiophenol/4-methoxythiophenol with 2-bromo-N-quinolin-8-yl-acetamide in the presence of sodium hydroxide in ethanol at 80 °C gave [C9H6N-NH-C(O)-CH2-S-Ar] [Ar = C6H5 (L1), C6H4Cl-4 (L2), C6H4Me-4 (L3), and C6H4-OMe-4 (L4)]. The corresponding reaction of L1-L4 with Na2PdCl4 in methanol at room temperature for 3 h resulted in complexes [(L1-H)PdCl] (C1), [(L2-H)PdCl] (C2), [(L3-H)PdCl] (C3), and [(L4-H)PdCl] (C4). All new compounds have been characterized by spectroscopic analyses. The structures of complexes C1, C3, and C4 have also been determined from single-crystal X-ray diffraction data. The cytotoxicities of L1-L4 and C1-C4 have been investigated for breast cancer 4T1 and pancreatic cancer MIA-PaCa-2 cells. The IC50 values for complexes C2 and C3 were observed to be comparable to or higher than those of cisplatin. The stressed morphology and cell death of cancerous cells were successfully observed through cellular morphology analysis and the assessment of cytoskeleton damage.

A novel cobalt(ii) acetate complex bearing lutidine ligand: a promising electrocatalyst for oxygen evolution reaction.

Developing cost-effective electrocatalysts using earth-abundant metal as an alternative to expensive precious metal catalyst remains a key challenge for researchers. Several strategies are being researched/tested for making low-cost transition metal complexes with controlled electron-density and coordination flexibility around the metal center to enhance their catalytic activity. Herein, we report a novel lutidine coordinated cobalt(ii) acetate complex [(3,5-lutidine)2Co(OAc)2(H2O)2] (1) as a promising electrocatalyst for oxygen evolution reaction (OER). Complex 1 was characterized by FT-IR, elemental analysis, and single crystal X-ray diffraction data. The structure optimization of complex 1 was also done using DFT calculation and the obtained geometrical parameters were found to be in good agreement with the parameters obtained from the solid state structure obtained through single crystal X-ray diffraction data. Further, the molecular electrostatic potential (MEP) maps analysis of complex 1 observed electron rich centers that were found to be in agreement with the solid-state structure. It was understood that the coordination of lutidine as a Lewis base and acetate moiety as a flexible ligand will provide more coordination flexibility around the metal center to facilitate the catalytic reaction. Further, the electron rich centers around metal center will also support the enhancement of their catalytic activity. Complex 1 shows impressive OER activity, even better than the state-of-the-art IrO2 catalyst, in terms of turnover frequency (TOF: 0.05) and onset potential (1.50 V vs. RHE). The TOF for complex 1 is two and half times higher, while the onset potential is ca. 20 mV lower, than the benchmark IrO2 catalyst studied under identical conditions.

Nickel Complexes Bearing ONS Chelating Ligands: A Promising Contender for In Vitro Cytotoxicity Effects on Human Pancreatic Cancer MIA-PaCa-2 Cells.

The highly chronic human pancreatic cancer cell is one of the major reasons for cancerous death. Nickel complexes are recently gaining interest in anticancer activities on different types of cancer cells. Hence, in this study, we synthesized and characterized a series of ONS donor ligands [2-HO-C6H4-CH═N-(C6H4)-SH] (L1), [2-OH-3-OMe-C6H3-CH═N-(C6H4)-SH] (L2), [2-OH-3,5-(C(Me)3)2-C6H2-CH═N-(C6H4)-SH] (L3), [2-OH-C6H4-CH═N-(C6H4)-SMe] (L4), [2-OH-3-OMe-C6H3-CH═N-(C6H4)-SMe] (L5), [2-OH-3,5-(C(Me)3)2-C6H2-CH═N-(C6H4)-SMe] (L6) and their Ni(II) metal complexes [(MeOH)Ni(L1-L1-4H)] (1), [(MeOH)Ni(L2-L2-4H)] (2), [(MeOH)Ni(L3-L3-4H)] (3), [(L4-H)2Ni] (4), [(L5-H)2Ni] (5), and [(L6-H)2Ni] (6). The single-crystal X-ray diffraction data of complexes 1 and 4 were collected to elucidate the geometry around the metal center. The anticancer activity of complexes 1-6 was investigated on human pancreatic cancer cell line MIA-PaCa-2, which revealed that complexes 4 and 6 were the most significantly effective in decreasing the cell viability of cancer cells at the lowest dose. The structure parameters obtained from single-crystal X-ray diffraction data are found to be in good agreement with the data from density functional theory and Hirshfeld surface analysis for complex 1.

Laryngeal histoplasmosis: masquerading malignancy.

Laryngeal histoplasmosis is a very rare cause of laryngitis which is encountered usually in the immunosuppressed states but can also occur in immunologically intact status. We report a rare case of laryngeal histoplasmosis in a man in his 60s, a chronic smoker who presented with a history of progressive hoarseness for 3 months. The glottic growth was biopsied. The rarity of diagnosis was aided by histopathological examination of the tissue, which revealed histoplasmosis. Management was done with intravenous liposomal amphotericin B and oral itraconazole with complete resolution of symptoms.