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Sookai S, Munro OQ. Spectroscopic and computational study of the interaction of Pt(II) pyrrole-imine chelates with human serum albumin. Dalton Trans 2023; 52:14774-14789. [PMID: 37698009 DOI: 10.1039/d3dt02039h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
Three bis(pyrrolide-imine) Pt(II) chelates were synthesised and characterized with different bridging alkyl groups, specifically 2-hydroxypropyl (1), 2,2-dimethylpropyl (2), and 1,2-(S,S)-(+)-cyclohexyl (3). Novel compounds 1 and 2 were analysed by single-crystal X-ray diffraction (space group P1̄). The asymmetric unit of 1 comprises three independent molecules linked by hydrogen bonds involving the OH groups, forming a trimeric supramolecular structure. The Pt(II) chelates were reacted with human serum albumin (HSA) to investigate how the ligand bound to the Pt(II) ion influences the compound's affinity for HSA. Fluorescence quenching data obtained for native HSA and HSA bound to site-specific probes (warfarin, subdomain IIA; ibuprofen, subdomain IIIA) indicated that the three Pt(II) chelates bind close enough (within ∼30 Å) to Trp-214 to quench its intrinsic fluorescence. The bimolecular quenching constant (kq) was 103-104 -fold higher than the maximum diffusion-controlled collision constant in water (1010 M s-1) at 310 K, while the affinity constants, Ka, ranged from ∼5 × 103 to ∼5 × 105 at 310 K, and followed the order 1 > 3 > 2. The reactions of 1 and 3 with HSA were enthalpically driven, while that for 2 was entropically driven. Macromolecular docking simulations (Glide XP) and binding site specificity assays employing site-specific probes and UV-vis CD spectroscopy indicated that 1 and 2 target Sudlow's site II in subdomain IIIA, minimally perturbing the tertiary structure of the protein. Well-resolved induced CD signals from 1 and 2 bound to HSA in subdomain IIIA were adequately simulated by hybrid QM:MM TD-DFT methods. We conclude that the structure of the bis(pyrrolide-imine) Pt(II) chelate measurably affects its uptake by HSA without detectable decomposition or demetallation. Such compounds could thus serve as metallodrug candidates capable of utilising an HSA-mediated cellular uptake pathway.
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Affiliation(s)
- Sheldon Sookai
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO WITS 2050, Johannesburg, South Africa.
| | - Orde Q Munro
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO WITS 2050, Johannesburg, South Africa.
- School of Chemistry University of Leeds, Woodhouse Lane, LS2 9JT, UK.
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2
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N,N-bis(2-quinolinylmethyl)benzylamine. MOLBANK 2021. [DOI: 10.3390/m1208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
N,N-bis(2-quinolinylmethyl)benzylamine (1) was synthesized under basic conditions from a pseudo-three-component reaction between benzylamine and two molecules of 2-(quinolinylmethyl)chloride, resulting in the formation of two N–C bonds in a single step. Compound (1) crystallizes in the triclinic system of the P-1 space group. The unit cell comprises a dimer of 1, in which the monomers are linked by two complementary hydrogen bonds between N1 and H′1–C′1 of another molecule. The dimers form chains along the a-axis through intermolecular interactions between the N′2 acceptor atoms and C″17 donors from molecules in the nearest neighboring dimer. These interactions form extended sheets of the dimers of 1, along the ab plane. The quinolinylmeth-2-yl groups of 1 lie in almost orthogonal planes and their N1/2(q) donor atoms are away from the apical amino N3 atom.
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Barry KL, Grimmer CD, Munro OQ, Akerman MP. Self-assembled supramolecular structures of O, N, N' tridentate imidazole-phenol Schiff base compounds. RSC Adv 2020; 10:7867-7878. [PMID: 35492155 PMCID: PMC9049879 DOI: 10.1039/c9ra10488g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 02/16/2020] [Indexed: 01/25/2023] Open
Abstract
Three imidazole-derived Schiff base compounds comprising an N-methyl imidazole group coupled to a phenol ring through an imine bond were synthesised. The structures differ by the substituent on the phenol ring at the 4-position: methyl (1), tert-butyl (2) and hydrogen (3). The compounds were synthesised using both a traditional reflux in solvent as well as an environmentally friendly solid-state reaction. Compounds (1)–(3) as well as the hemihydrate of (3) were all studied by single crystal X-ray diffraction. The asymmetric unit of compound (1) consists of two nominally planar molecules linked by hydrogen bonds to form a dimeric supramolecular structure. This dimeric structure was ubiquitous for the anhydrous forms of (1)–(3). The complementary hydrogen bonding motif between the imidazole N atoms and the phenol OH results in a stable 16-membered hydrogen-bonded ring. The asymmetric unit of (3) comprises two symmetry-independent molecules one of which has co-planar imidazole and phenol rings while the other shows a significantly oblique orientation. The hemihydrate of (3) similarly forms extensive hydrogen bonds, though in the form of a water-bridged dimeric structure. The hydrogen bond lengths (D⋯A) for compounds (1)–(3) are relatively short, ranging from 2.662(1) to 2.688(1) Å. DFT was used to understand the relative stability of the monomeric and dimeric species. These showed the hydrogen-bonded supramolecular structures were ca. 101 kJ mol−1 lower in energy than the non-interacting monomers. Scan simulations were used to calculate the total energy of the molecule as a function of phenyl ring rotation and showed why the expected planar configuration for a conjugated π-system was not observed experimentally. The barrier to rotation was found to be relatively low, 7.97(6) kJ mol−1, with the lowest energy conformations subtending dihedral angles of 22.319, 24.265 and 25.319° for molecules (1), (2) and (3), respectively. The electrostatic potential maps are able to succinctly explain the stability of the hydrogen bonds through the partial charges of the interacting atoms. TD-DFT simulations and analysis of the simulated and experimental UV/visible spectra suggest that the dimeric supramolecular structure is a stable species in solution. This was confirmed through 1H NMR titrations and an equilibrium constant of 0.16(5) M−1 was estimated. Three imidazole-derived Schiff base compounds comprising an N-methyl imidazole group coupled to a phenol ring through an imine bond were synthesised. The solid state and solution state supramolecular structures as well as energetics are explored.![]()
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Affiliation(s)
- Kristy-Lyn Barry
- School of Chemistry and Physics, University of KwaZulu-Natal Private Bag X01, Scottsville Pietermaritzburg 3209 South Africa
| | - Craig D Grimmer
- School of Chemistry and Physics, University of KwaZulu-Natal Private Bag X01, Scottsville Pietermaritzburg 3209 South Africa
| | - Orde Q Munro
- Molecular Sciences Institute, School of Chemistry, WITS University Johannesburg South Africa
| | - Matthew P Akerman
- School of Chemistry and Physics, University of KwaZulu-Natal Private Bag X01, Scottsville Pietermaritzburg 3209 South Africa
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Chen GH, Leu WJ, Guh JH, Lin CH, Huang JH. Synthesis, characterization and cancer cell growth inhibition activity of ruthenium(II) complexes bearing bidentate pyrrole-imine ligands. J Organomet Chem 2018. [DOI: 10.1016/j.jorganchem.2018.05.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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5
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Towards the synthesis of prenylated phloroglucinol derivatives: An X-ray crystallographic and DFT study of unexpected reaction products. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2018.03.097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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6
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An unusual asymmetric pseudomacrocyclic free base ligand and nickel(II) chelate: X-ray crystallographic and DFT studies. Polyhedron 2017. [DOI: 10.1016/j.poly.2016.12.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Joondan N, Jhaumeer-Laulloo S, Caumul P, Akerman M. Synthesis, physicochemical, and biological activities of novel N-acyl tyrosine monomeric and Gemini surfactants in single and SDS/CTAB-mixed micellar system. J PHYS ORG CHEM 2016. [DOI: 10.1002/poc.3675] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Nausheen Joondan
- Department of Chemistry, Faculty of Science; University of Mauritius; Réduit Mauritius
| | | | - Prakashanand Caumul
- Department of Chemistry, Faculty of Science; University of Mauritius; Réduit Mauritius
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Zikode M, Ojwach SO, Akerman MP. Structurally rigid bis(pyrazolyl)pyridine Zn(II) and Cu(II) complexes: Structures and kinetic studies in ring-opening polymerization of ε-caprolactone. Appl Organomet Chem 2016. [DOI: 10.1002/aoc.3556] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mnqobi Zikode
- School of Chemistry & Physics; University of KwaZulu-Natal; Pietermaritzburg Campus, Private Bag X01 Scottsville 3209 South Africa
| | - Stephen O. Ojwach
- School of Chemistry & Physics; University of KwaZulu-Natal; Pietermaritzburg Campus, Private Bag X01 Scottsville 3209 South Africa
| | - Matthew P. Akerman
- School of Chemistry & Physics; University of KwaZulu-Natal; Pietermaritzburg Campus, Private Bag X01 Scottsville 3209 South Africa
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Chatturgoon T, Akerman MP. X-ray and DFT-calculated structures of bis[N-(quinolin-8-yl)benzamidato-κ(2)N,N']copper(II). ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2016; 72:234-8. [PMID: 26942434 DOI: 10.1107/s2053229616003120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 02/22/2016] [Indexed: 11/10/2022]
Abstract
The application of transition metal chelates as chemotherapeutic agents has the advantage that they can be used as a scaffold around which ligands with DNA recognition elements can be anchored. The facile substitution of these components allows for the DNA recognition and binding properties of the metal chelates to be tuned. Copper is a particularly interesting choice for the development of novel metallodrugs as it is an endogenous metal and is therefore less toxic than other transition metals. The title compound, [Cu(C16H11N2O)2], was synthesized by reacting N-(quinolin-8-yl)benzamide and the metal in a 2:1 ratio. Ligand coordination required deprotonation of the amide N-H group and the isolated complex is therefore neutral. The metal ion adopts a flattened tetrahedral coordination geometry with the ligands in a pseudo-trans configuration. The free rotation afforded by the formal single bond between the amide group and phenyl ring allows the phenyl rings to rotate out-of-plane, thus alleviating nonbonded repulsion between the phenyl rings and the quinolyl groups within the complex. Weak C-H...O interactions stabilize a dimer in the solid state. Density functional theory (DFT) simulations at the PBE/6-311G(dp) level of theory show that the solid-state structure (C1 symmetry) is 79.33 kJ mol(-1) higher in energy than the lowest energy gas-phase structure (C2 symmetry). Natural bond orbital (NBO) analysis offers an explanation for the formation of the C-H...O interactions in electrostatic terms, but the stabilizing effect is insufficient to support the dimer in the gas phase.
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Affiliation(s)
- Teshica Chatturgoon
- School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
| | - Matthew P Akerman
- School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
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Nyamato GS, Ojwach SO, Akerman MP. Ethylene oligomerization studies by nickel(ii) complexes chelated by (amino)pyridine ligands: experimental and density functional theory studies. Dalton Trans 2016; 45:3407-16. [DOI: 10.1039/c5dt04667j] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Activation of (amino)pyridine nickel(ii) complexes 1–4 with either EtAlCl2 or methylaluminoxane (MAO), produced active ethylene oligomerization catalysts to afford mostly butenes and hexenes and octenes as minor products.
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Affiliation(s)
- George S. Nyamato
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Scottsville
- South Africa
| | - Stephen O. Ojwach
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Scottsville
- South Africa
| | - Matthew P. Akerman
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Scottsville
- South Africa
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Akerman KJ, Venter C, Hunter LA, Akerman MP. Palladium(II) complexes of 2-pyridylmethylamine and 8-aminoquinoline: A crystallographic and DFT study. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.02.077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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An X-ray crystallographic and DFT study of bis(pyrrolide-imine) nickel(II) Schiff base chelates. Inorganica Chim Acta 2014. [DOI: 10.1016/j.ica.2014.06.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Nyamato GS, Ojwach SO, Akerman MP. Packing forces in dichloridobis(3,5-diphenyl-1H-pyrazole-κN(2))cobalt(II) dichloromethane hemisolvate. Acta Crystallogr C 2014; 70:780-3. [PMID: 25093359 DOI: 10.1107/s2053229614015411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 07/01/2014] [Indexed: 11/10/2022] Open
Abstract
The title compound, [CoCl2(C15H12N2)2]·0.5CH2Cl2, was crystallized from a binary mixture of dichloromethane and hexane and a dimeric supramolecular structure was isolated. The Co(II) centre exhibits a distorted tetrahedral geometry, with two independent pyrazole-based ligands occupying two coordination sites and two chloride ligands occupying the third and fourth coordination sites. The supramolecular structure is supported by complementary hydrogen bonding between the pyrazole NH group and the chloride ligand of an adjacent molecule. This hydrogen-bonding motif yields a ten-membered hydrogen-bonded ring. Density functional theory (DFT) simulations at the PBE/6-311G level of theory were used to probe the solid-state structure. These simulations suggest that the chelate undergoes a degree of conformational distortion from the lowest-energy geometry to allow for optimal hydrogen bonding in the solid state.
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Affiliation(s)
- George S Nyamato
- School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa
| | - Stephen O Ojwach
- School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa
| | - Matthew P Akerman
- School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa
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