Auxiliary Part of Ligand Mediated Unique Coordination Chemistry of Copper (II)

Six N,N,O-donor Schiff-base ligands, HL1-HL6, [HL1/HL2/HL3= {2-(2-piperazin-1-yl)ethylimino)methyl)-4-(Cl/H/Me)-phenol}; HL4/HL5/HL6={2-(2-morpholine/piperidine/ pyrrolidine 1-yl)ethylimino)methyl)-4-chlorophenol}, have been designed by combining 5-R-2-hydroxy-benzaldehyde, (R=Cl/H/Me) and N-(2-aminoethyl)-Y, (Y=piperazin/morpholine/ piperidine/pyrrolidine) with the view to explore the role of R and X (part of Y excluding coordinating N) on the coordination chemistry of Cu (II) in presence of bromide as counter anion. HL1-HL6 formed in situ on reaction with Cu(II)Br2 produce complexes 1\u20136, respectively. Complex 1, [Cu(II)2Cu(I)2(L1)(MeOH)2Br7.30], is a mixed valence Cu(I)-Cu(II) species having phenyl ring brominated at ortho position with 0.65 occupancy. Complexes 2\u20134 are mononuclear species with general formula [Cu{L2/L3/L4)}Br2]. Complexes [Cu3(L5)Br4] (5) and [Cu3(L6)Br4] (6) are trinuclear species having similar structure but exhibit different magnetic property, 5 is ferro- (J= +16.64 cm1 ) and 6 is antiferromegnetic (J= \u201311.76 cm1). The influence of R and X on bromination, magnetic property and nuclearity issues have been rationalized by DFT calculations

Supplementary data for the article: Adhikary, J.; Chakraborty, A.; Dasgupta, S.; Chattopadhyay, S. K.; Kruszynski, R.; Trzesowska-Kruszynska, A.; Stepanović, S.; Gruden-Pavlović, M.; Swart, M.; Das, D. Unique Mononuclear Mn II Complexes of an End-off Compartmental Schiff Base Ligand: Experimental and Theoretical Studies on Their Bio-Relevant Catalytic Promiscuity. Dalton Transactions 2016, 45 (31), 12409–12422. https://doi.org/10.1039/c6dt00625f

Supplementary material: [https://doi.org/10.1039/c6dt00625f]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2294

Unique mononuclear Mn-II complexes of an end-off compartmental Schiff base ligand: experimental and theoretical studies on their bio-relevant catalytic promiscuity

Three new mononuclear manganese(II) complexes, namely [Mn(HL)(2)]center dot 2ClO(4) (1), [Mn(HL)(N(CN)(2)) (H2O)(2)]center dot ClO4 (2) and [Mn(HL)(SCN)(2)] (3) [LH = 4-tert-butyl-2,6-bis-[(2-pyridin-2-yl-ethylimino)-methyl]-phenol], have been synthesized and structurally characterized. An "end-off" compartmental ligand (LH) possesses two symmetrical compartments with N2O binding sites but accommodates only one manganese atom instead of two due to the protonation of the imine nitrogen of one compartment. Although all three complexes are mononuclear, complex 1 is unique as it has a 1 : 2 metal to ligand stoichiometry. The catalytic promiscuity of complexes 1-3 in terms of two different bio-relevant catalytic activities namely catecholase and phenoxazinone synthase has been thoroughly investigated. EPR and cyclic voltametric studies reveal that radical formation rather than metal centered redox participation is responsible for their catecholase-like and phenoxazinone synthase-like catalytic activity. A computational approach suggests that imine bond bound radical generation rather than phenoxo radical formation is most likely responsible for the oxidizing properties of the complexes.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3657

Alumina-supported Mn(III) and Fe(III) complexes of tridentate Schiff base ligand having ONO-donor sites: Syntheses, characterization and olefin epoxidation study

Two new mononuclear Schiff base complexes, [MLCl(H2O)2] [M = Mn(III) or Fe(III); H2L = 2-phenoliminomethylphenol], have been prepared and characterized by elemental analysis, thermogravimetric analysis, UV-vis and FT-IR spectroscopy, cyclic voltammetry and ESI-MS analyses. Both complexes show excellent alkenes epoxidation activity and thus these complexes have been infused over neutral active alumina to prepare the heterogeneous catalysts. These catalysts are characterized by solid UV-vis and FT-IR spectroscopy, thermogravimetric and powder XRD and FE-SEM studies. Finally, the catalysts have been studied for the epoxidation of different types of olefins in presence of terminal oxidants (PhIO and t-BHP) and are easily recyclable

Phenoxazinone synthase activity of two iron(III) complexes comprising the same Schiff base ligand: Biomimetic functional model and mechanistic investigation

A new 4,4′-bipyridine (4,4′-byp) mediated 1D- polymeric FeIII complex (complex 1) of Schiff base ligand H2L, a 1:2 condensation product of 1,2-diaminopropane and salicylaldehyde, has been synthesized. Complex 1 is structurally characterized by single crystal X-ray diffraction. A phenoxo bridged dinuclear FeIII complex (complex 2) of analogous ligand has been synthesized also. Dioxygen activation in terms of Phenoxazinone synthase activity using o-aminophenol (OAPH) as a model substrate catalyzed by both the complexes are thoroughly investigated here. ESI-MS spectral study reveals that polynuclear complex 1 dissociates into mononuclear units while dissolve in methanol during catalytic study. The kinetic study illustrates that both the complexes have well competence towards o-aminophenol oxidation where dinuclear FeIII species demonstrate higher activity than mononuclear intermediate species. Important finding from the mass spectral and electrochemical study provide significant information of the mechanistic pathway of the functioning phenoxazinone synthase like activity of synthesized iron complexes

Zinc and cadmium complexes of a Schiff base ligand derived from diaminomaleonitrile and salicylaldehyde: Syntheses, characterization, photoluminescence properties and DFT study

1463-1468Zn(II) and Cd(II) complexes of a 1+1 condensed Schiff base derived from salicylaldehyde and diaminomaleonitrile has been synthesized and characterized. Electronic and photoluminescence spectral properties of the complexes as well as the free ligand have been investigated and a thorough DFT study has been performed to rationalize the spectral behavior

Dinuclear cobalt(II) complexes of Schiff-base compartmental ligands: Syntheses, crystal structure and bio-relevant catalytic activities

Three dicobalt(II) complexes, namely [Co2(L1H)(H2O)2(OAc)2](OAc)2 (1), [Co2(L2)(H2O)2(OAc)2](OAc) (2) and [Co2(L3)(H2O)2(OAc)2](OAc) (3) of the p-cresol based \u2018\u2018end-off\u2019\u2019 compartmental ligands 2,6-bis(R-iminomethyl)- 4-methyl-phenolato, where R = N-ethylpiperazine for L1, 2-ethylpyridine for L2 and N-ethylpiperidine for L3, have been synthesized and characterized by common physicochemical techniques, and in the case of complex 1 also by single crystal X-ray diffraction analysis. All the complexes show excellent catecholase-like activity, monitored not only with 3,5-di-tert-butylcatechol but also with tetrachlorocatechol, a substrate reluctant to be oxidized. To the best of our knowledge, to date no cobalt complex has been found in the literature to manifest such activity. The complexes are observed to interact efficiently with CT-DNA and on incubation (employing plasmid pTZ57/R/T DNA) they exhibit concentration dependent DNA cleavage activity. The mechanisms related to the DNA cleavage and catecholase-like activities have been investigated. The cytotoxicity of the complexes has also been examined through an MTT assay

A radical pathway in catecholase activity with nickel(ii) complexes of phenol based \u201cend-off\u201d compartmental ligands

Seven dinuclear and one dinuclear based dicyanamide bridged polymeric NiII complexes of phenol based compartmental ligands (HL1\u2013HL4) have been synthesized with the aim to investigate their catecholaselike activity and to evaluate the most probable mechanistic pathway involved in this process. The complexes have been characterized by routine physicochemical studies as well as by X-ray single crystal structure analyses namely [Ni2(L2)(SCN)3(H2O)(CH3OH)] (1), [Ni2(L4)(SCN)3(CH3OH)2] (2), [Ni2(L2)(SCN)2(AcO)- (H2O)] (3), [Ni2(L4)(SCN)(AcO)2] (4), [Ni2(L2)(N3)3(H2O)2] (5), [Ni2(L4)(N3)3(H2O)2] (6), [Ni2(L1)(AcO)2- (N(CN)2)]n (7) and [Ni2(L3)(AcO)2(N(CN)2)] (8), [SCN = isothiocyanate, AcO = acetate, N3 = azide, and N(CN)2 = dicyanamide anion; L1\u20134 = 2,6-bis(R2-iminomethyl)-4-R1-phenolato, where R1 = methyl and tert-butyl, R2 = N,N-dimethyl ethylene for L1\u20132 and R1 = methyl and tert-butyl, R2 = 2-(N-ethyl) pyridine for L3\u20134]. A UV-vis spectrophotometric study using 3,5-di-tert butylcatechol (3,5-DTBC) reveals that all the complexes are highly active in catalyzing the aerobic oxidation of (3,5-DTBC) to 3,5-di-tert-butylbenzoquinone (3,5-DTBQ) in methanol medium with the formation of hydrogen peroxide

Relation between the catalytic efficiency of the synthetic analogues of catechol oxidase with their electrochemical property in the Free State and substrate-bound state

A library of 15 dicopper complexes as synthetic analogues of catechol oxidase has been synthesized with the aim to determine the relationship between the electrochemical behavior of the dicopper(II) species in the absence as well as in the presence of 3,5-di-tert-butylcatechol (3,5-DTBC) as model substrate and the catalytic activity, kcat, in DMSO medium. The complexes have been characterized by routine physicochemical techniques as well as by X-ray single-crystal structure analysis in some cases. Fifteen \u201cend-off\u201d compartmental ligands have been designed as 1 + 2 Schiff-base condensation product of 2,6-diformyl-4-R-phenol (R = Me, tBu, and Cl) and five different amines, N-(2-aminoethyl)- piperazine, N-(2-aminoethyl)pyrrolidine, N-(2-aminoethyl)- morpholine, N-(3-aminopropyl)morpholine, and N-(2-aminoethyl)piperidin

Influence of para substituents in controlling photophysical behavior and different non-covalent weak interactions in zinc complexes of a phenol based "end-off" compartmental ligand

Three dinuclear zinc(II) complexes with "end-off" compartmental ligands, namely 2,6-bis(N-ethylmorpholine-iminomethyl)-4-R-phenol (I: R = -CH3, Cl, tBu) were synthesized with the aim of exploring the role of the para substituent present in the ligand backbone in controlling the structural diversity, photophys. properties and different weak interactions of the complexes. The complexes are [Zn2L1(CH3CO2)2]1/2[Zn(NCS)4].3/2H2O (1), [Zn2L2(CH3CO2)2]1/2[Zn(NCS)4] (2), and [Zn2L3(CH3CO2)2]1/2[Zn(NCS)4] (3),. All three species, with the general formula 2[Zn2L(CH3COO)2][Zn(NCS)4], show the complex anion Zn(NCS)42- as a common structural feature decisive for crystn. All of them possess several noncovalent weak interactions where the nature of the "R'' group plays an essential role as exposed by DFT study. Besides exhibiting fluorescence behavior, the complexes also show para substitution controlled phosphorescence both at room and low temp. Anisotropy studies suggest the existence of complexes 2 and 3 as dimers in soln. The origins of the unusual room temp. phosphorescence and fluorescence behavior of the complexes were rationalized in the light of theor. calcns. [on SciFinder(R)