Research

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17 pages, 3268 KiB

Open AccessArticle

Salen-like Chromium and Aluminum Complexes as Catalysts in the Copolymerization of Epoxides with Cyclic Anhydrides for the Synthesis of Polyesters

by Federica Santulli, Ilaria Grimaldi, Daniela Pappalardo, Marina Lamberti and Mina Mazzeo

Int. J. Mol. Sci. 2023, 24(12), 10052; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms241210052 - 13 Jun 2023

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Abstract

Chromium and aluminum complexes bearing salalen ligands were explored as catalysts for the ring-opening copolymerization (ROCOP) of succinic (SA), maleic (MA), and phthalic (PA) anhydrides with several epoxides: cyclohexene oxide (CHO), propylene oxide (PO), and limonene oxide (LO). Their behavior was compared with [...] Read more.

Chromium and aluminum complexes bearing salalen ligands were explored as catalysts for the ring-opening copolymerization (ROCOP) of succinic (SA), maleic (MA), and phthalic (PA) anhydrides with several epoxides: cyclohexene oxide (CHO), propylene oxide (PO), and limonene oxide (LO). Their behavior was compared with that of traditional salen chromium complexes. A completely alternating enchainment of monomers to provide pure polyesters was achieved with all the catalysts when used in combination with 4-(dimethylamino)pyridine (DMAP) as the cocatalyst. Poly(propylene maleate-block-polyglycolide), a diblock polyester with a precise composition, was obtained by switch catalysis, in which the same catalyst was able to combine the ROCOP of propylene oxide and maleic anhydride with the ring-opening polymerization (ROP) of glycolide (GA) through a one-pot procedure, starting from an initial mixture of the three different monomers. Full article

(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes Based on Schiff Base Ligands: Structure-Property Relationships and Applications)

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12 pages, 4218 KiB

Open AccessArticle

Schiff Bases Functionalized with T-Butyl Groups as Adequate Ligands to Extended Assembly of Cu(II) Helicates

by Sandra Fernández-Fariña, Isabel Velo-Heleno, Miguel Martínez-Calvo, Marcelino Maneiro, Rosa Pedrido and Ana M. González-Noya

Int. J. Mol. Sci. 2023, 24(10), 8654; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms24108654 - 12 May 2023

Cited by 2 | Viewed by 935

Abstract

The study of the inherent factors that influence the isolation of one type of metallosupramolecular architecture over another is one of the main objectives in the field of Metallosupramolecular Chemistry. In this work, we report two new neutral copper(II) helicates, [Cu₂(L [...] Read more.

The study of the inherent factors that influence the isolation of one type of metallosupramolecular architecture over another is one of the main objectives in the field of Metallosupramolecular Chemistry. In this work, we report two new neutral copper(II) helicates, [Cu₂(L¹)₂]·4CH₃CN and [Cu₂(L²)₂]·CH₃CN, obtained by means of an electrochemical methodology and derived from two Schiff-based strands functionalized with ortho and para-t-butyl groups on the aromatic surface. These small modifications let us explore the relationship between the ligand design and the structure of the extended metallosupramolecular architecture. The magnetic properties of the Cu(II) helicates were explored by Electron Paramagnetic Resonance (EPR) spectroscopy and Direct Current (DC) magnetic susceptibility measurements. Full article

(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes Based on Schiff Base Ligands: Structure-Property Relationships and Applications)

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15 pages, 3439 KiB

Open AccessArticle

Multifunctional Zn(II) Coordination Polymer as Highly Selective Fluorescent Sensor and Adsorbent for Dyes

by Mohd. Muddassir, Abdullah Alarifi, Naaser A. Y. Abduh, Waseem Sharaf Saeed, Abdulnasser Mahmoud Karami and Mohd. Afzal

Int. J. Mol. Sci. 2023, 24(10), 8512; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms24108512 - 10 May 2023

Cited by 1 | Viewed by 1423

Abstract

A new Zn(II)-based coordination polymer (1) comprising the Schiff base ligand obtained by the condensation of 5-aminosalicylic acid and salicylaldehyde has been synthesized. This newly synthesized compound has been characterized by analytical and spectroscopic methods, and finally, by single-crystal X-ray diffraction [...] Read more.

A new Zn(II)-based coordination polymer (1) comprising the Schiff base ligand obtained by the condensation of 5-aminosalicylic acid and salicylaldehyde has been synthesized. This newly synthesized compound has been characterized by analytical and spectroscopic methods, and finally, by single-crystal X-ray diffraction technique in this study. The X-ray analysis reveals a distorted tetrahedral environment around the central Zn(II) center. This compound has been used as a sensitive and selective fluorescent sensor for acetone and Ag⁺ cations. The photoluminescence measurements indicate that in the presence of acetone, the emission intensity of 1 displays quenching at room temperature. However, other organic solvents caused meagre changes in the emission intensity of 1. Additionally, the fluorescence intensity of 1 has been examined in the presence of different ketones viz. cyclohexanone, 4-heptanone, and 5-nonanone, to assess the interaction between the C=O group of the ketones and the molecular framework of 1. Moreover, 1 displays a selective recognition of Ag⁺ in the aqueous medium by an enhancement in its fluorescence intensity, representing its high sensitivity for the detection of Ag⁺ ions in a water sample. Additionally, 1 displays the selective adsorption of cationic dyes (methylene blue and rhodamine B). Hence, 1 showcases its potential as an excellent luminescent probe to detect acetone, other ketones, and Ag⁺ with an exceptional selectivity, and displaying a selective adsorption of cationic dye molecules. Full article

(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes Based on Schiff Base Ligands: Structure-Property Relationships and Applications)

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10 pages, 3096 KiB

Open AccessArticle

Surprising Solid-State ESIPT Emission from Apparently Ordinary Salicyliden Glycinates Schiff Bases

by Mateusz M. Tomczyk, Łukasz Przypis, Tomohiro Shiraki, Joachim Kusz, Maria Książek, Dawid Janas and Nikodem Kuźnik

Int. J. Mol. Sci. 2022, 23(23), 14955; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms232314955 - 29 Nov 2022

Cited by 2 | Viewed by 1599

Abstract

Excited-State Intramolecular Photon Transfer (ESIPT) is known for the geometry-related phenolic and imine groups. The Schiff bases formed upon condensation of salicyl aldehyde and glycine led to the formation of ESIPT models. A series of alkali metal salicyliden glycinates were analyzed by X-ray [...] Read more.

Excited-State Intramolecular Photon Transfer (ESIPT) is known for the geometry-related phenolic and imine groups. The Schiff bases formed upon condensation of salicyl aldehyde and glycine led to the formation of ESIPT models. A series of alkali metal salicyliden glycinates were analyzed by X-ray diffraction of their monocrystals and spectroscopy measurements. The X-ray analysis revealed varied hydration levels between the salts. They adapted trans geometry on the imine groups and mostly anticlinal conformation with the neighboring atoms, which is different from the other structurally-related compounds in literature. Fluorescence of these compounds was found for the crystalline forms only. Protonation of the imine nitrogen atom and further proton distribution was consistent with the ESIPT theory, which also explained the observed fluorescence with the highest Stokes shift of 10,181 cm⁻¹ and 10.1% of fluorescence quantum yield for the sodium salt. Full article

(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes Based on Schiff Base Ligands: Structure-Property Relationships and Applications)

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19 pages, 7684 KiB

Open AccessArticle

3-Aminopyridine Salicylidene: A Sensitive and Selective Chemosensor for the Detection of Cu(II), Al(III), and Fe(III) with Application to Real Samples

by Yousef M. Hijji, Rajeesha Rajan and Amjad M. Shraim

Int. J. Mol. Sci. 2022, 23(21), 13113; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms232113113 - 28 Oct 2022

Cited by 5 | Viewed by 1173

Abstract

Interest in developing selective and sensitive metal sensors for environmental, biological, and industrial applications is mounting. The goal of this work was to develop a sensitive and selective sensor for certain metal ions in solution. The goal was achieved via (i) preparing the [...] Read more.

Interest in developing selective and sensitive metal sensors for environmental, biological, and industrial applications is mounting. The goal of this work was to develop a sensitive and selective sensor for certain metal ions in solution. The goal was achieved via (i) preparing the sensor ((E)-2-((pyridine-3-ylimino)methyl)phenol) (3APS) using microwave radiation in a short time and high yield and (ii) performing spectrophotometric titrations for 3APS with several metal ions. 3APS, a Schiff base, was prepared in 5 min and in a high yield (95%) using microwave-assisted synthesis. The compound was characterized by FTIR, XRD, NMR, and elemental analysis. Spectrophotometric titration of 3APS was performed with Al(III), Ba(II), Cd(II), Co(II), Cu(II), Fe(III), Mn(II), Ni(II), and Zn(II). 3APS showed good abilities to detect Al(III) and Fe(III) ions fluorescently and Cu(II) ion colorimetrically. The L/M stoichiometric ratio was 2:1 for Cu(II) and 1:1 for Al(III) and Fe(III). Low detection limits (μg/L) of 324, 20, and 45 were achieved for Cu(II), Al(III), and Fe(III), respectively. The detection of aluminum was also demonstrated in antiperspirant deodorants, test strips, and applications in secret writing. 3APS showed high fluorescent selectivity for Al(III) and Fe(III) and colorimetric selectivity towards Cu(II) with detection limits lower than corresponding safe drinking water guidelines. Full article

(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes Based on Schiff Base Ligands: Structure-Property Relationships and Applications)

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22 pages, 20130 KiB

Open AccessArticle

Experimental and Computational Studies on the Interaction of a Dansyl-Based Fluorescent Schiff Base Ligand with Cu²⁺ Ions and CuO NPs

by Jesús Sanmartín-Matalobos, Pilar Bermejo-Barrera, Ignacio Pérez-Juste, Matilde Fondo, Ana M. García-Deibe and Yeneva Alves-Iglesias

Int. J. Mol. Sci. 2022, 23(19), 11565; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms231911565 - 30 Sep 2022

Cited by 2 | Viewed by 1204

Abstract

We studied the interaction of Cu²⁺ ions and CuO nanoparticles with the fluorescent Schiff base ligand H₃L, which derives from the condensation of 4-formyl-3-hydroxybenzoic acid with N-(2-aminobenzyl)-5-(dimethylamino)naphthalene-1-sulfonamide (DsA). A detailed assignment of the most significant bands of the electronic [...] Read more.

We studied the interaction of Cu²⁺ ions and CuO nanoparticles with the fluorescent Schiff base ligand H₃L, which derives from the condensation of 4-formyl-3-hydroxybenzoic acid with N-(2-aminobenzyl)-5-(dimethylamino)naphthalene-1-sulfonamide (DsA). A detailed assignment of the most significant bands of the electronic and infrared spectra of H₃L and DsA was performed using DFT methods, based on both crystal structures. The affinity of H₃L to react with Cu²⁺ ions in solution (K_B = 9.01 10³ L mol⁻¹) is similar to that found for the Cu²⁺ ions present on the surface of CuO NPs (K_B = 9.84 10³ L mol⁻¹). Fluorescence spectroscopic measurements suggest five binding sites for H₃L on the surface of the CuO NPs used. The µ-XRF analysis indicates that a polycrystalline sample of CuO-H₃L NPs contains 15:1 Cu:S molar ratio (CuO:H₃L). ATR-FTIR spectroscopy, supported by DFT calculations, showed that the HL²⁻ (as a phenolate and sulfonamide anion) is coordinated to superficial Cu²⁺ ions of the CuO NPs through their azomethine, sulphonamide, and phenolic groups. A solution of H₃L (126 ppb) shows sensitive responses to CuO NPs, with a limit of detection (LOD) of 330 ppb. The working range for detection of CuO NPs with [H₃L] = 126 ppb was 1.1–9.5 ppm. Common metal ions in water, such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Fe³⁺, and Al³⁺ species, do not interfere significantly with the detection of CuO NPs. Full article

(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes Based on Schiff Base Ligands: Structure-Property Relationships and Applications)

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Review

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20 pages, 11280 KiB

Open AccessReview

Metal Complexes with Schiff Bases: Data Collection and Recent Studies on Biological Activities

by Maria Stefania Sinicropi, Jessica Ceramella, Domenico Iacopetta, Alessia Catalano, Annaluisa Mariconda, Camillo Rosano, Carmela Saturnino, Hussein El-Kashef and Pasquale Longo

Int. J. Mol. Sci. 2022, 23(23), 14840; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms232314840 - 27 Nov 2022

Cited by 17 | Viewed by 3660

Abstract

Metal complexes play a crucial role in pharmaceutical sciences owing to their wide and significant activities. Schiff bases (SBs) are multifaceted pharmacophores capable of forming chelating complexes with various metals in different oxidation states. Complexes with SBs are extensively studied for their numerous [...] Read more.

Metal complexes play a crucial role in pharmaceutical sciences owing to their wide and significant activities. Schiff bases (SBs) are multifaceted pharmacophores capable of forming chelating complexes with various metals in different oxidation states. Complexes with SBs are extensively studied for their numerous advantages, including low cost and simple synthetic strategies. They have been reported to possess a variety of biological activities, including antimicrobial, anticancer, antioxidant, antimalarial, analgesic, antiviral, antipyretic, and antidiabetic ones. This review summarizes the most recent studies on the antimicrobial and antiproliferative activities of SBs-metal complexes. Moreover, recent studies regarding mononuclear and binuclear complexes with SBs are described, including antioxidant, antidiabetic, antimalarial, antileishmanial, anti-Alzheimer, and catecholase activities. Full article

(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes Based on Schiff Base Ligands: Structure-Property Relationships and Applications)

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16 pages, 19652 KiB

Open AccessReview

Photofunctions in Hybrid Systems of Schiff Base Metal Complexes and Metal or Semiconductor (Nano)Materials

by Takashiro Akitsu, Barbara Miroslaw and Shanmugavel Sudarsan

Int. J. Mol. Sci. 2022, 23(17), 10005; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms231710005 - 02 Sep 2022

Cited by 6 | Viewed by 2111

Abstract

Composite materials very often provide new catalytic, optical or other physicochemical properties not observed for each component separately. Photofunctions in hybrid systems are an interesting topic of great importance for industry. This review presents the recent advances, trends and possible applications of photofunctions [...] Read more.

Composite materials very often provide new catalytic, optical or other physicochemical properties not observed for each component separately. Photofunctions in hybrid systems are an interesting topic of great importance for industry. This review presents the recent advances, trends and possible applications of photofunctions of hybrid systems composed of Schiff base metal complexes and metal or semiconductor (nano)materials. We focus on photocatalysis, sensitization in solar cells (DSSC—dye sensitized solar cell), ligand-induced chirality and applications in environmental protection for Cr(VI) to Cr(III) reduction, in cosmetology as sunscreens, in real-time visualization of cellular processes, in bio-labeling, and in light activated prodrug applications. Full article

(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes Based on Schiff Base Ligands: Structure-Property Relationships and Applications)

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