S. M. Mahbub-ul-Haque Majumder

Bio: S. M. Mahbub-ul-Haque Majumder is an academic researcher from University of Chittagong. The author has contributed to research in topics: Enantioselective synthesis & Chemistry. The author has an hindex of 2, co-authored 2 publications receiving 138 citations.

Synthesis, characterization and biological activities of some new nickel(II), copper(II), zinc(II) and cadmium(II) complexes of quadridentate SNNS ligands

Abstract: The quadridentate ligands, prepared by condensation ofS-methyl- andS-benzyldithiocarbazate with glyoxal, form stable crystalline complexes of gerferal formula, M(SNNS) (M=NiII, CuII, ZnII and CdII; SNNS−2=ligand dianion). The NiII complexes are diamagnetic but electronic spectral data support a dimeric five-coordinate geometry. Based on magnetic and spectral data, a five-coordinate square-pyramidal structure is also assigned to the copper(II) complexes. The ZnII and CdII complexes are polymeric and octahedral. The Schiff bases and metal complexes display good antifungal and antibacterial properties.

Asymmetric Total Syntheses of (-)-Lycoramine, (-)-Lycoraminone, (-)-Narwedine, and (-)-Galanthamine.

Abstract: A concise asymmetric total synthesis of naturally occurring Amaryllidaceae alkaloids sharing dihydrobenzofuran scaffolds, (-)-galanthamine (1a), (-)-lycoramine (1b), (-)-narwedine (2a), and (-)-lycoraminone (2b), is reported. Orthoester Johnson-Claisen rearrangement of allyl alcohol (+)-9 (98% ee) in diisopropylethylamine furnished enantioenriched cyclohexene (+)-8 (97.4% ee) with a quaternary stereogenic center.

Asymmetric Total Syntheses of (–)-Dihydromaritidine and (–)-Oxomaritidine

Abstract: A concise catalytic asymmetric approach to naturally occurring Amaryllidaceae alkaloids sharing 5,10b-ethanophenanthridine skeleton, (-)-oxomaritidine (1c), (-)-dihydromaritidine (1d), (-)-maritidine (1a), and (-)-epi-maritidine (1e) has been envisioned. The key intermediate of this strategy has been realized via a Pd(0)-catalyzed decarboxylative allylation (DcA) of an 2-arylcyclohexanone derived allylenolcarbonate (87% yield with 96% ee).

Syntheses, Crystal Structures, and Antibacterial Activities of Four Schiff Base Complexes of Copper and Zinc

Abstract: Four Schiff base complexes, [Cu2(L1)2(μ-NCS)2] (1), [Cu2(L2)2(μ-N3)2] (2), Cu[Cu(CH3COO)(L3)]2 (3), and [Zn{Zn(C3H4N2)(L3)}2(NO3)](NO3) (4) (where L1 = 2-[(pyridin-2-ylmethylimino)methyl]phenol, L2 = 1-[(pyridin-2-ylmethylimino)methyl]naphthalen-2-ol, and L3 = bis(salicylidene)-1, 3-propanediamine), were synthesized and characterized by elemental analyses, infrared spectroscopy, and single crystal X-ray determinations. Both 1 and 2 are structurally similar di-nuclear complexes, which are located at crystallographic inversion centers (with the center of the central Cu2N2 ring). In 1, each copper atom has a slightly distorted square pyramidal configuration, coordinated by two nitrogen atoms and one oxygen atom from L1 and another two terminal nitrogen atoms from two bridging thiocyanate anions. The Cu···Cu separation is 3.466(3) A. The structure of 2 is similar to that of 1, with Cu···Cu separation of 3.368(2) A. Both 3 and 4 are linear tri-nuclear complexes. In 3, the central Cu2+ ion is located on an inversion centre and has a distorted octahedral coordination involving four bridging O atoms from two Schiff base ligands (L3) in the equatorial plane and one O atom from each bridging acetate group in the axial positions. The coordination around the terminal Cu2+ ions is irregular-square pyramidal, with two O and two N atoms of L3 in the basal plane and one O atom from an acetate group in the apical position. The acetate bridges linking the central and terminal Cu2+ ions are mutually trans. The Cu···Cu separation is 3.009(3) A. In 4, the coordination configuration of the central and the terminal zinc atoms are similar to that of the 3, with Zn···Zn separation of 3.153(4) A. The three Schiff bases and the corresponding three copper complexes exhibit good antibacterial properties, while the zinc complex 4 has nearly no. Synthesen, Kristallstrukturen und antibakterielle Wirkung von vier Schiff-Base-Komplexen von Kupfer und Zink Die Schiff-Base-Komplexe, [Cu2(L1)2(μ-NCS)2] (1), [Cu2(L2)2(μ-N3)2] (2), [Cu{Cu(CH3COO)(L3)}2] (3), and [Zn{Zn(C3H4N2)(L3)}2(NO3)](NO3) (4)(L1 = 2-[(pyridin-2-ylmethylimino)methyl]phenol, L2 = 1-[(pyridin-2-ylmethylimino)methyl]naphthalen-2-ol und L3 = bis(salicyliden)-1, 3-propanediamin) wurden synthetisiert und mittels Elementaranalyse, IR-Spektroskopie und Einkristallstrukturanalysen charakterisiert. 1 und 2 sind strukturell ahnliche, zweikernige Komplexe, mit einem Symmetriezentrum in dem zentralen Cu2N2-Ring. In 1 haben die Kupferatome leicht verzerrte quadratisch-pyramidale Koordination und werden von zwei Stickstoffatomen und einem Sauerstoffatom von L1 und zwei anderen terminalen Stickstoffatomen zweier verbruckender Thiocyanat-Anionen koordiniert. Der Cu···Cu-Abstand in 1 betragt 3.466(3) A, der in 2 3.368(2) A. 3 und 4 sind lineare Dreikern-Komplexe. In 3 befindet sich das zentrale Cu2+-Ion auf einem Symmetriezentrum und ist verzerrt oktaedrisch von vier Brucken-O-Atomen zweier Schiff-Base-Liganden (L3) aquatorial und durch je ein O-Atom der beiden Brucken-Acetatgruppen in den Axial-Positionen koordiniert. Die Koordination der terminalen Cu2+-Ionen ist irregular-quadratisch-pyramidal mit je zwei O- und N-Atomen von L3 basal und einem O-Atom einer Acetat-Gruppe in der Apical-Position. Die Acetatbrucken, die die zentralen und terminalen Cu2+-Iions verbinden, sind wechselseitig trans positioniert. Der Cu···Cu-Abstand betragt 3.009(3) A. In 4 ist die Koordination der zentralen und terminalen Zinkatome ahnlich zu der von 3 mit einem Zn···Zn-Abstand von 3.153(4) A. Die drei Schiffschen Basen und entsprechenden drei Kupferkomplexe zeigen gute antibakterielle Eigenschaften, wahrend 4 nahezu unwirksam ist.

Complexes of a tridentate ONS Schiff base. Synthesis and biological properties

Abstract: Several new complexes of a tridentate ONS Schiff base derived from the condensation of S-benzyldithiocarbazate with salicylaldehyde have been characterised by elemental analyses, molar conductivity measurements and by i.r. and electronic spectra. The Schiff base (HONSH) behaves as a dinegatively charged ligand coordinating through the thiolo sulphur, the azomethine nitrogen and the hydroxyl oxygen. It forms mono-ligand complexes: [M(ONS)X], [M=NiII, CuII, CrIII, SbIII, ZnII, ZrIV or UVI with X = H2O, Cl]. The ligand produced a bis-chelated complex of composition [Th(ONS)2] with ThIV. Square-planar structures are proposed for the NiII and CuII complexes. Antimicrobial tests indicate that the Schiff base and five of the metal complexes of CuII, NiII, UVI, ZnII and SbIII are strongly active against bacteria. NiII and SbIII complexes were the most effective against Pseudomonas aeruginosa (gram negative), while the CuII complex proved to be best against Bacillus cereus (gram positive bacteria). Antifungal activities were also noted with the Schiff base and the UVI complex. These compounds showed positive results against Candida albicans fungi, however, none of them were effective against Aspergillus ochraceous fungi. The Schiff base and its zinc and antimony complexes are strongly active against leukemic cells (CD50 = 2.3–4.3 μg cm−3) while the copper, uranium and thorium complexes are moderately active (CD50 = 6.9–9.5 μg cm−3). The nickel, zirconium and chromium complexes were found to be inactive.