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Special Issue "Research about Vital Organic Chelates and Metal Ion Complexes Volume II"

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A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Organic Crystalline Materials".

Deadline for manuscript submissions: closed (30 October 2023) | Viewed by 7017

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Dr. Moamen S. Refat

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Department of Chemistry, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
Interests: charge-transfer complexes; metal–acid complexes; schiff base complexes; metal–drug interactions; metal–dye complexes; crystal structures
Special Issues, Collections and Topics in MDPI journals

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Dear Colleagues,

Metal ion complexes is a rapidly developing field with enormous potential for applications that provides new possibilities for the pharmaceutical industry. It is expected that increasing knowledge about the role of minerals in biochemistry will provide an area for designing new drugs in many other areas as well, for example, neuropharmacology and anti-potency agents. Advances in coordination chemistry rely heavily on an understanding of not only the thermodynamics of reactions, but also the kinetics of mineral complexes under biologically relevant conditions. Metals are essential cellular components that function in many biochemical processes that are indispensable to living organisms. Transition metal complexes are important in catalysis, material synthesis, photochemistry, and biological systems. Inorganic medicinal chemistry can exploit the unique properties of metal ions to design new drugs. The use of metals and their complexes for medicinal purposes has been present throughout history. With advances in inorganic chemistry, the role of transition metal complexes as therapeutic compounds is becoming increasingly important. Recent advances in inorganic chemistry have made it possible to form a few transition metal complexes of organic interest that can be used as therapeutic agents. This review clarifies the role of metals and recent advances in medicinal organic biochemistry with new approaches to the design and application of innovative metal-based drugs.

Dr. Moamen S. Refat
Guest Editor

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Keywords

metal complexes
metal-based drugs
medicinal inorganic chemistry
crystals
nanomaterials and applications
composites

Published Papers (7 papers)

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Research

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17 pages, 4282 KiB

Open AccessArticle

D,L-Citrullinato-bipyridine Copper Complex: Experimental and Theoretical Characterization

Diego Ramírez-Contreras

Amalia García-García

Angel Mendoza

Laura E. Serrano-de la Rosa

Brenda L. Sánchez-Gaytán

Francisco J. Melendez

María Eugenia Castro

and

Enrique González-Vergara

Crystals 2023, 13(9), 1391; https://doi.org/10.3390/cryst13091391 - 19 Sep 2023

Viewed by 626

Abstract

Citrulline is a non-protein amino acid that acts as a metabolic intermediate in the urea cycle and arginine synthesis. It is present in some foods, although its name derives from watermelon (Citrullus vulgaris), from which it was first identified. Under normal conditions, Citrulline exists as a zwitterion in aqueous solutions since its carboxylic and amine groups can act as Lewis donors to chelate metal cations. In addition, Citrulline possesses in the aliphatic chain a terminal ureide group, which could also coordinate. Although Citrulline is comparable to other classical amino acids, its coordination chemistry has yet to be explored. Only two metal complexes have been reported, and the copper complex is a polymeric and insoluble material. As part of our search for active Casiopeina^® analogs, we created a more soluble complex by combining 2,2′-Bipyridine into a new mixed material, resulting in the mononuclear complex [Cu(Bipy)(Citr)(H₂O)(NO₃)]·H₂O. Single-crystal X-ray diffraction, spectroscopic methods (FT-IR, UV-Vis, Raman), and mass spectrometry characterized the material. Interestingly, both isomers of Citrulline, R(D), and S(L) are present in the same crystal. In addition, the molecular structure and electronic properties of the complex were calculated using density functional theory (DFT). Non-covalent interactions were characterized using the atoms-in-molecules (AIM) approach and Hirshfeld surface (HS) analysis. This ternary complex containing Citrulline and 2,2′-Bipyridine will be used for docking calculations and preliminary biological studies using calf thymus DNA (CT-DNA) and plasmid pUC19 as a first approximation to cytotoxic activity against cancer cell lines. Full article

(This article belongs to the Special Issue Research about Vital Organic Chelates and Metal Ion Complexes Volume II)

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15 pages, 3324 KiB

Open AccessArticle

Complexes of the Antibiotic Drug Oxolinic Acid with Fe(III), Zn(II), Ca(II), and Mg(II) Ions: Preparation, Characterization, and In Vitro Evaluation of Biological Activity

Abdulrahman A. Almehizia

and

Crystals 2023, 13(7), 1012; https://doi.org/10.3390/cryst13071012 - 25 Jun 2023

Cited by 2 | Viewed by 516

Abstract

The chemical reaction between quinolone antibiotic oxolinic acid (OA) and Fe(III), Zn(II), Ca(II), and Mg(II) ions results in the formation of metal-based complexes with the following formulas: [Fe(OA)(H₂O)₂Cl₂]·2H₂O, [Zn(OA)(H₂O)Cl]·2H₂O, [Ca(OA)(H₂O)Cl], and [Mg(OA)(H₂O)Cl]. We used analytical (C, N, H, Cl, metal analysis) and spectral (FT-IR, ¹H NMR, UV-visible) data to structurally characterize the synthesized metal-based complexes of the OA molecule. We found that the OA molecule utilizes the two oxygen atoms of the carboxylate group and the pyridone C=O group to bind the investigated metal ions. The morphological properties of the synthesized OA complexes were assessed using X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The biological properties, specifically antibacterial and antifungal activity, of the synthesized complexes were evaluated in vitro using the Kirby–Bauer disc diffusion protocol with five bacterial and three fungal strains. The complex containing Ca(II) ions exhibited remarkable antibacterial and antifungal activity against all tested microbial strains, surpassing or equaling the potency of the standard drugs (streptomycin for antibacterial assays and ketoconazole for antifungal assays). Full article

(This article belongs to the Special Issue Research about Vital Organic Chelates and Metal Ion Complexes Volume II)

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14 pages, 4539 KiB

Open AccessArticle

Schiff-Based Modified Bentonite Clay Composites for Wastewater Treatment: Experimental and DFT-Based Analysis

Sadaf Mutahir

Fakhira Yaqoob

Muhammad Asim Khan

Amnah Mohammed Alsuhaibani

Amr S. Abouzied

Moamen S. Refat

and

Bader Huwaimel

Crystals 2023, 13(5), 806; https://doi.org/10.3390/cryst13050806 - 11 May 2023

Cited by 1 | Viewed by 938

Abstract

A new bentonite clay composite was synthesized by modifying bentonite clay and Schiff base (SB). The purpose of the composite was to eliminate methylene blue (MB) from wastewater. To characterize its efficacy, several spectroscopic techniques (UV-Visible spectroscopy, FTIR, SEM, and XRD) were used. The interactions between the adsorbent dose, pH, initial dye concentration, and contact duration were also tested to evaluate the adsorption capacity of the adsorbent. The results demonstrated that changes in the modification led to a considerable increase in adsorption capacity, with a maximum monolayer adsorption capacity of 258 mg/g being achieved at pH 11. Based on the batch experiments, molecular dynamics simulations, and DFT studies, the pseudo-second-order model described the sorption of MB on the bentonite clay composite the best. It was found that the adsorption of MB on the bentonite clay composite primarily followed a monolayer adsorption mechanism. Using the Langmuir isotherm model, the experimental results were consistent, indicating the monolayer adsorption mechanism. Finally, this study demonstrated that the bentonite-SB adsorbent had enormous promise for the elimination of methylene blue (MB) from wastewaters, as evidenced by the electron density mapping within the molecular electrostatic potential plot and the electrostatic potential graphing within the iso-surface plot. Full article

(This article belongs to the Special Issue Research about Vital Organic Chelates and Metal Ion Complexes Volume II)

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14 pages, 1043 KiB

Open AccessArticle

Synthesis, Spectroscopic Characterization and Thermal Studies of Polymer-Metal Complexes Derived from Modified Poly Styrene-Alt-(Maleic Anhydride) as a Prospects for Biomedical Applications

Abdulrahman A. Almehizia

Amnah Mohammed Alsuhaibani

and

Crystals 2023, 13(5), 728; https://doi.org/10.3390/cryst13050728 - 26 Apr 2023

Cited by 1 | Viewed by 1112

Abstract

Eight polymer-metal complexes were synthesized from complexation of divalent Mn(II), Ni(II), Co(II), and Cu(II) metal ions with modified polystyrene-alt-(maleic anhydride) (PSMAP and PSMAM) ligands. The structures of these new complexes were characterized using a variety of techniques, including magnetic moment susceptibility, conductance measurements, FT-IR spectroscopy, ultraviolet-visible (UV-VIS), thermogravimetric analysis (TGA), as well as scanning electron microscopy (SEM). All metal-polymer complexes have a non-electrolytic nature based on conductance measurements. The polymer molecule behaves as neutral bidentate NO ligand through O atoms of carbonyl (C=O) and N atoms of amide (O=C-NH). Divalent Mn²⁺, Ni²⁺, Co²⁺ and Cu²⁺ complexes have an octahedral geometry based on their electronic spectra and magnetic values. Based on thermal analysis data, those new complexes are more thermally stable than the ligands. SEM and TEM are manipulated to give the surface structure and the particle size measurements where they give different shapes and sizes of the synthesized complexes. Full article

(This article belongs to the Special Issue Research about Vital Organic Chelates and Metal Ion Complexes Volume II)

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12 pages, 2527 KiB

Open AccessArticle

Synthesis and Spectroscopic Characterizations of Some Essential Metal Ion (Mg^II, Ca^II, Zn^II, and Fe^III) Pipemidic Acid Chemotherapeutic Agent Complexes

Asma S. Al-Wasidi

Crystals 2023, 13(4), 596; https://doi.org/10.3390/cryst13040596 - 01 Apr 2023

Cited by 1 | Viewed by 713

Abstract

The assignments structures of the four 1:1 pipemidic acid (pipH)–magnesium(II), calcium(II), zinc(II), and iron(III) complexes, [Mg(pip)(H₂O)₃(Cl)].6H₂O, [Ca(pip)(H₂O)₃(Cl)].2H₂O, [Zn(pip)(H₂O)₃(Cl)].4H₂O, and [Fe(pip)(H₂O)₂(Cl)₂].6H₂O, (where pip = deprotonated pipemidic), were synthesized through the chemical reactions of MgCl₂.6H₂O, CaCl₂.2H₂O, ZnCl₂, and FeCl₃.6H₂O metal salt chlorides with pipH chemotherapeutic agent ligand in a methanolic solvent. The microanalytical analysis CHN, conductance, (infrared (FTIR) and electronic (UV–Vis.)) spectra, and thermogravimetric measurements (TG) have been utilized to discuss the solid isolated complexes. The X-ray powder diffraction (XRD) analysis and the transmission electron microscopy (TEM) confirm the nanostructured form of the synthesized pip complexes. The deprotonated pipH ligand is coordinated to Mg(II), Ca(II), Zn(II), and Fe(III) metal ions through the two oxygen atoms of the carbonyl (quinolone group) and carboxylic group. The thermodynamic parameters (energy, E*), (entropy, ΔS*), (enthalpy, ΔH*), and (Gibbs free energy, ΔG*) of activation have been estimated based on thermogravimetric curves using “Coats–Redfern and Horowitz–Metzeger non–isothermal” methods. Full article

(This article belongs to the Special Issue Research about Vital Organic Chelates and Metal Ion Complexes Volume II)

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18 pages, 6007 KiB

Open AccessArticle

Synthesis of Bivalent Ni(II), Cu(II) and Zn(II) Complexes of Azodicarbonamide in Mixture of Methanol and Aqueous Solvents: Spectral Characterizations and Anti-Microbial Studies

Abdulrahman A. Almehizia

Mohamed A. Al-Omar

Ahmed M. Naglah

Abdulrahman M. Al-Obaid

and

Crystals 2023, 13(3), 367; https://doi.org/10.3390/cryst13030367 - 21 Feb 2023

Cited by 1 | Viewed by 1614

Abstract

Three new transition-metal complexes were produced by refluxing azodicarbonamide (ADCA) with nickel(II), copper(II), and zinc(II) solutions in a mixture of 50% (v/v) methanol and water. The magnitude of chelation between metal ions and ligand molecules was assessed by FT-IR, UV, elemental analysis, TGA, conductivity, mass, and magnetic susceptibility measurements. FT-IR analysis suggested a bi-dentate chelation in all complexes, which takes place through the N-azo and O-carbonyl groups. Based on the measurement of magnetic moments and spectral analysis, a distorted octahedral geometry was proposed for Ni(II) and Cu(II) complexes, whereas zinc complex showed a hexa-coordinated geometry. The optical band gaps of the nickel(II), copper(II) and zinc(II) complexes were found to be 1.91, 2.50, and 1.96 eV, respectively, which means that they can be employed as semiconductors and that they are in the same range as highly effective photovoltaic materials. The Urbach energy parameters were also estimated from other optical parameters. The biological activity of azodicarbonamide and its synthesized complexes has been screened against the selected gram bacteria (+ve) and fungi. Full article

(This article belongs to the Special Issue Research about Vital Organic Chelates and Metal Ion Complexes Volume II)

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Review

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17 pages, 13668 KiB

Open AccessReview

Imidazol(in)ium-2-Thiocarboxylate Zwitterion Ligands: Structural Aspects in Coordination Complexes

Fernando Carrillo-Hermosilla

and

Humberto Rodríguez-Solla

Crystals 2023, 13(9), 1304; https://doi.org/10.3390/cryst13091304 - 26 Aug 2023

Viewed by 1021

Abstract

Azolium-2-thiocarboxylate zwitterion ligands have emerged as a promising class of compounds in the field of coordination chemistry due to their unique structural features and versatile applications. These ligands are characterized by a positively charged azolium ring and a negatively charged thiocarboxylate moiety, making them capable of forming stable coordination complexes with various metal ions. One of the key structural aspects that make these ligands attractive for coordination chemistry is their ability to adopt diverse coordination modes with metal centers. The nature of these ligands enables them to engage in both monodentate and bidentate coordination, resulting in the formation of chelated complexes with enhanced stability and controlled geometry or the formation of polynuclear structures. This versatility in coordination behavior allows for the design of tailored ligands with specific metal-binding preferences, enabling the creation of unique and finely tuned coordination architectures. The azolium-2-thiocarboxylate zwitterionic ligands offer a promising platform for the design of coordination complexes with diverse structural architectures. Full article

(This article belongs to the Special Issue Research about Vital Organic Chelates and Metal Ion Complexes Volume II)

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Special Issue "Research about Vital Organic Chelates and Metal Ion Complexes Volume II"

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