Formation Of Metal Complexes Research Articles

Isolated Dipolar ONN Schiff Base Regioisomers: Synthesis, Characterization and Crystallographic Study.

Organic compounds with 1,3-diketone or 3-amino enone functional groups are extremely important as they can be converted into a plethora of carbo- or heterocyclic derivatives or can be used as ligands in the formation of metal complexes. Here, we have achieved the preparation of a series of non-symmetrical β-ketoenamines (O,N,N proligand) of the type (4-MeOC6H4)C(=O)CH=C(R)NH(Q) obtained through the Schiff base condensation of 1,3-diketones (1-anisoylacetone, 1-anisyl-3-(4-cyanophenyl)-1,3-propanedione, and 1-anisyl-3-(4,4,4-trifluorotolyl)-1,3-propanedione) functionalized with electron donor and electron-withdrawing substituents and 8-aminoquinoline (R = CH3, 4-C6H4CN, 4-C6H4CF3; Q = C9H7N). Schiff base ketoimines with a pendant quinolyl moiety were isolated as single regioisomers in yields of 22-56% and characterized with FT-IR, 1H NMR, and UV-visible spectroscopy, as well as single-crystal X-ray crystallography, which allowed for the elucidation of the nature of the isolated regioisomers. The regioselectivity of the condensation of electronically unsymmetrical 1,3-diaryl-1,3-diketones with 8-aminoquinoline was studied by 1H NMR, providing regioisomer ratios of ~3:1 and ~2:1 in the case of CN and CF3 substituents, respectively. The electronic effects correlate well with the difference between the Hammett σ+ coefficients of the two para substituents on the aryl rings.

Enhancing Sensitivity of Nuclear Magnetic Resonance in Biomolecules: Parahydrogen-Induced Hyperpolarization in Synthetic Disulfide-Rich Miniproteins.

Hyperpolarization of small peptides by parahydrogen-induced polarization (PHIP) to increase the sensitivity of nuclear magnetic resonance (NMR) techniques is well established, while its application to larger biopolymers is still a mainly unexplored area. A particular challenge is the presence of folding-essential disulfide bridges. They tend to form metal complexes, thus hampering catalytic hydrogenation, a prerequisite for PHIP. We applied the PHIP technique to enhance NMR signal intensity in cystine-knot miniproteins─highly ordered peptide architectures covalently stabilized by three disulfides. To achieve PHIP, we introduced an l-propargyl tyrosine label at different positions in three synthetic open-chain variants of a natural trypsin inhibitor MCoTI-II. For the folded cystine knot, we observed NMR signal enhancements of up to 499 in methanol, 307 in a D2O-methanol mixture, and 964 for the cysteine-bearing reduced precursor. Trypsin inhibition assays elucidated that introducing a PHIP label into the terminal regions is preferable to alterations within the functional loop to preserve bioactivity. Substitution of the native tyrosine resulted in the highest bioactivity. A drastic reduction in PHIP enhancement was observed in the presence of trypsin due to slower hydrogenation, conditioned by the accessibility of the label within an enzyme-inhibitor complex.

Microwave-assisted Synthesis of Pyrroles, Pyridines, Chromenes, Coumarins, and Betti Bases via Alcohol Dehydrogenation with Chroman-4-one Amino Ligands

: This study outlines the development of a novel approach utilizing microwave assistance for the alcohol dehydrogenative reaction. The process is catalyzed by manganese (II) and cobalt (II) in conjunction with chroman-4-one amino ligands. This research introduces a unique catalytic system capable of synthesizing various heterocyclic compounds, including pyrroles, pyridines, Betti bases, chromenes, and coumarins via alcohol dehydrogenation. The synthesis involved the preparation and characterization of a series of chroman- 4-one amino ligands (C1-C6) using standard analytical techniques. These ligands, in combination with MnCl2‧4H2O and CoCl2, demonstrated remarkable catalytic activity, effectively driving alcohol dehydrogenation. The catalytic cycle was initiated by the in-situ formation of metal complexes with the ligands during the reaction. Characterization using ESI-MS confirmed the presence of metal complexes (Int-1) and other intermediates (Int-II and Int-III) throughout the catalytic cycle. Additionally, the controlled experiment corroborated the efficacy of the catalytic system, evidenced by the evolution of H2 gas.

A Review: Recent Advances in Chemistry and Applications of 2,4-Dihydroxybenzaldehyde Oxime and Its Transition Metal Complexes

This review presents a comprehensive overview of the recent advances in the chemistry and applications of 2,4-dihydroxybenzaldehyde oxime (DHBO) and its transition metal complexes. DHBO, characterized by its unique hydroxyl and oxime functional groups, has gained significant attention due to its versatile reactivity and potential applications across various fields, including pharmaceuticals, catalysis, and environmental science. Recent synthetic methodologies, including microwave-assisted techniques and green chemistry approaches, have improved the efficiency and sustainability of DHBO production. The formation of transition metal complexes with DHBO has been a focal point of research, revealing enhanced catalytic properties and biological activities compared to the free ligand. These complexes have shown promise in organic synthesis, particularly in oxidation and reduction reactions, as well as in drug development, exhibiting antimicrobial and anticancer properties. Furthermore, the potential of DHBO and its metal complexes in environmental remediation, particularly in removing heavy metals and pollutants, underscores their significance in addressing contemporary environmental challenges. This review also provides current knowledge on the synthesis, characterization, and applications of DHBO and its transition metal complexes, highlighting their importance in both academic research and industrial applications. By elucidating the multifaceted roles of DHBO, this work aims to pave the way for future research and innovation in this promising area of study.

A facile double-signal ratiometric sensor of creatinine based on silver nanoparticles/thionine acetate/Mxenes with intrinsic self-calibration property

In this work, a ratiometric double signals electrochemical sensing platform was constructed for creatinine (Cre) analysis employing silver nanoparticles (AgNPs)@ MXenes/thionine acetate (THAT) composites. The synthesis of MXenes/THAT composites was utilized to modify on the surface of a screen-printed electrode (SPE) via dripping coating, followed by the electro-deposition of AgNPs. While the anodic current of the AgNPs decreased in the presence of Cre due to the competive reaction for forming metal complexes, the current of THAT remained invariant, which attained a ratiometric response. Under optimized conditions, the response current ratio (IAg/ITHAT) decreases while the concentration of Cre increased linearly between 0 ∼ 1.2 mM, with 0.01 μM as a adaptive detection limit. It provided a new sensing platforming for employing double-signals nanostructures with remarkable stability and sensitivity to design ratiometic sensors for analysis of Cre in human urine samples with real-time.

Chiral Self-Sorting Process With C2 Symmetric Bisimidazoline Ligands.

We have studied the coordination chemistry of chiral imidazoline-based C2-symmetric ligands with zinc (II) and copper (II). Two types of bisimidazoline ligands were studied, one with the free amine (BIM-H) and the other with the amine protected by a toluene sulfonyl group in position 6 (BIM-Ts). The complexes formed were isolated, purified, and characterized, in particular by X-ray diffraction studies and CD in the case of the enantiopure complexes. By playing with the choice of ligand system (enantiopure or racemate), we were able to show that the selective formation of homoleptic and heteroleptic metal complexes can be controlled by means of the chiral molecular instruction of bisimidazoline ligands.

Examining Metal Complexes Formed from New Schiff Base ‎Ligand ‎Derived from Benzene Carbaldehyde: Evaluation of Anti-‎biofilm and ‎Anti-bacterial Properties

One of the most difficult tasks in modern medical societies is the process of identifying a cure for many infectious diseases caused by drug-resistant microbes. Therefore, it has become necessary to discover new compounds that work in this regard. The currently prepared Schiff base, derived from thiazole, has a biological activity against bacteria and biofilms and its activity increases when it is associated with copper, zinc and platinum ions and forms metal complexes. This study highlights the synthesis and evaluation of novel biological compounds as inhibitors of bacterial growth and biofilms. A three newly complexes are resulting from the reaction of a new Schiff base ligand (LC) with metal ions (Zn, Cu, Pt). The new ligand (LC) was prepared from the reaction of precursor (P) and benzenecarbaldehyde. The prepared compounds were characterized by 1H&13CNMR, FTIR, UV-Vis, Magnetic susceptibility, CHNS and Molar conductivity. It was determined that the anti-bacterial activity of the newly synthesized Lc and (Cu-Lc) was mightily significant towards more antibiotic-resistant bacteria and had low (MIC) values. Like that, anti-biofilm inhibitory of the same compounds showed 100% of clinical isolates of P. aeruginosa and S. aureus in 16 and 32 mg/ml respectively, whereas (Zn-Lc) were inhibited 100% in 4 mg/ml. On the other hand (Pt-Lc) inhibited 100 % in 2 mg/ ml. Good yield was obtained from the synthesis of new compounds from the starting material. They can be potential candidates as inhibitors of bacteria and biofilms.

The Role of Low-Molecular-Weight Organic Acids in Metal Homeostasis in Plants.

Low-molecular-weight organic acids (LMWOAs) are essential O-containing metal-binding ligands involved in maintaining metal homeostasis, various metabolic processes, and plant responses to biotic and abiotic stress. Malate, citrate, and oxalate play a crucial role in metal detoxification and transport throughout the plant. This review provides a comparative analysis of the accumulation of LMWOAs in excluders, which store metals mainly in roots, and hyperaccumulators, which accumulate metals mainly in shoots. Modern concepts of the mechanisms of LMWOA secretion by the roots of excluders and hyperaccumulators are summarized, and the formation of various metal complexes with LMWOAs in the vacuole and conducting tissues, playing an important role in the mechanisms of metal detoxification and transport, is discussed. Molecular mechanisms of transport of LMWOAs and their complexes with metals across cell membranes are reviewed. It is discussed whether different endogenous levels of LMWOAs in plants determine their metal tolerance. While playing an important role in maintaining metal homeostasis, LMWOAs apparently make a minor contribution to the mechanisms of metal hyperaccumulation, which is associated mainly with root exudates increasing metal bioavailability and enhanced xylem loading of LMWOAs. The studies of metal-binding compounds may also contribute to the development of approaches used in biofortification, phytoremediation, and phytomining.

Effects of Heterogeneous Mixing of Imidazolium-Based Ionic Liquids with Alcohols on Complex Formation of Ni(II) Ion.

Understanding the complex formation of metal ions in room-temperature ionic liquids (ILs) is essential for the application of ILs in solvent extraction. Nevertheless, the research on metal complex formation in ILs lags behind other applications. The complex formation equilibria may be influenced by specific interactions among the metal ion, ligand molecule, and IL cation and anion. In the present investigation, the complex formation of Ni2+ with ethanol (EtOH) and methanol (MeOH) molecules in ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([CNmim][TFSA], where N represents the alkyl chain lengths of 2 and 8) was discussed in terms of the microscopic interactions among alcohol molecules, [CNmim]+ and [TFSA]-, and the mesoscopic mixing states of alcohols in [CNmim][TFSA], with N = 2-12. The microscopic interaction of alcohol molecules with the imidazolium ring H atoms in the ILs was evaluated by using ATR-IR and 1H and 13C NMR spectroscopies. The self-hydrogen bonding of alcohol molecules was clarified from the O-H stretching vibration of alcohol molecules. MeOH molecules can be more strongly hydrogen-bonded with themselves than EtOH molecules due to the less steric hindrance and the weaker dispersion force of MeOH with the IL cation's alkyl chain. In fact, small-angle neutron scattering (SANS) experiments revealed the more heterogeneous mixing of MeOH with the ILs by the self-hydrogen bonding among MeOH molecules than EtOH. The longer the IL cation's alkyl chain, the more the MeOH clusters significantly form. In contrast, the formation of EtOH clusters becomes weaker with elongating the alkyl chain. Ultraviolet (UV)-visible spectroscopic measurements on Ni2+-[CNmim][TFSA]-alcohol solutions with N = 2 and 8 revealed that di-, tetra-, and hexa-alcohol-Ni2+ complexes are formed in both the ILs. With N = 2, the stabilities of Ni2+-EtOH and Ni2+-MeOH complexes are comparable in the IL. However, with N = 8, the complexes are more stable in the EtOH solutions than in the MeOH solutions. This is because the less heterogeneous mixing of EtOH molecules with the IL results in the larger enthalpic contribution in the complex formation, as shown by the thermodynamic parameters estimated by the van't Hoff plots on the stability constants at several temperatures.

Copper(II) and Zinc(II) Complexes with Bacterial Prodigiosin Are Targeting Site III of Bovine Serum Albumin and Acting as DNA Minor Groove Binders.

The negative environmental and social impacts of food waste accumulation can be mitigated by utilizing bio-refineries' approach where food waste is revalorized into high-value products, such as prodigiosin (PG), using microbial bioprocesses. The diverse biological activities of PG position it as a promising compound, but its high production cost and promiscuous bioactivity hinder its wide application. Metal ions can modulate the electronic properties of organic molecules, leading to novel mechanisms of action and increased target potency, while metal complex formation can improve the stability, solubility and bioavailability of the parent compound. The objectives of this study were optimizing PG production through bacterial fermentation using food waste, allowing good quantities of the pure natural product for further synthesizing and evaluating copper(II) and zinc(II) complexes with it. Their antimicrobial and anticancer activities were assessed, and their binding affinity toward biologically important molecules, bovine serum albumin (BSA) and DNA was investigated by fluorescence emission spectroscopy and molecular docking. The yield of 83.1 mg/L of pure PG was obtained when processed meat waste at 18 g/L was utilized as the sole fermentation substrate. The obtained complexes CuPG and ZnPG showed high binding affinity towards target site III of BSA, and molecular docking simulations highlighted the affinity of the compounds for DNA minor grooves.

Novel hydroxy-tagged bis-dihydrazothiazole derivatives: Synthesis, antimicrobial capacity and formation of some metal chelates with iron, cobalt and zinc ions

Until today, microbialinfectionsepitomize a seriousuniversal health threat. Subsequently, developing a potential antimicrobialprototype remains an urgent, global necessity. Despite several reports discussing the biological utility of some bis-thiazoles, the use of bis-dihydrazothiazoles and their corresponding metal chelates as potent antimicrobials, is yet to be explored. The current report outlines an attempt to fill that void by representing a successful synthesis of a new class of bis-dihydrazothiazoles as well as three of their transition metal chelates and their use as potential antimicrobials. This report presents the design of some novel hydroxy-tagged bis-dihydrazothiazoles 6a-e and bis-dihydrazothiazolones 9a-evia the reaction of a bis-aldehyde thiosemicarbazone 3, as a common synthetic precursor, with two groups of hydrazonoyl halide derivatives 4a-e and 7a-e. The chelation affinity of these novel bis-dihydrazothiazoles to behave as neutral tridentate ligands coordinating to the metal ions; Fe(III), Co(II), or Zn(II) through azomethine-N, thiazole-S, and azo-N atoms to form metal complexes with a metal/ligand ratio of 2:1 was confirmed. In-vitro, antimicrobial screening of the novel hydroxy-tagged bis-dihydrazothiazole derivatives, as well as a selected group of their transition metal chelate complexes [M2L], was inspected, and the data weremeasured incomparisonto those of ketoconazole and gentamycin as antimicrobial reference standards. Most bis-dihydrazothiazoles 6a-e and bis-dihydrazothiazolones 9a-e showed decent to excellent antimicrobial activities against the screened microbes, but the chloro-substituted bis dihydrazothiazole derivatives 6c and 9c showed exceptional inhibition of Bacillus subtilis (20 mm), Escherichia coli (25 mm), and Candida albicans (19 mm), and Salmonella typhimurium (19 mm), respectively. Additionally, amongst the three synthesized metal complexes [M2L], only the zinc complex, [Zn2L] showed remarkable inhibition of both Staphylococcus aureus (21 mm) and Salmonella typhimurium (19 mm) compared to the reference standard Gentamycin, and was more potent than the free ligand, 6a itself (no activity and 11 mm respectively). Antimicrobial inspection was assessed by the agar well diffusion assay method against all bacterial and fungal strains. Magnetic moment, diffused reflectance, FT-IR, 1H NMR, molar conductivity, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope(SEM) were among the many techniques used to elucidate the structures of all novel hydroxy-tagged bis-heterocyclic ligands and their metal chelate complexes.

Preparation and characterization of pyrimidine‐cored covalent organic frameworks for heavy metal removal

AbstractIn this work, two novel pyrimidine‐cored covalent organic frameworks TpTap‐COF and TpTan‐COF were synthesized for the first time and used for the adsorption of heavy metal ions in aqueous solution. Both COFs are nanofiber clusters with preferable crystallinity and thermal stability. The impact parameters such as pH value, shaking time, initial concentration, and temperature were studied by batch adsorption experiments in the multi‐metal ions system. The adsorption of six metal ions onto COFs follows the pseudo‐second‐order kinetic model and the Freundlich isotherm model, which is a chemical adsorption process that occurs on non‐uniform surfaces. The adsorption rate is determined by both film diffusion and intraparticle diffusion. Further research on the adsorption of copper ions onto COFs indicates the formation of metal complexes between O#N#N/O#O chelating sites in the COF skeleton and Cu ions through the sharing of lone pair electrons.

Innovative bis-dihydrazothiazolone derivatives with a 1,4-xylenyl spacer: Design, antimicrobial prospective and construction of several transition metal chelates with iron, cobalt and zinc

Several new xylenyl-spaced bis-dihydrazothiazoles 6a-e and bis-dihydrazothiazolones 9a-e were synthesized by the simple reaction between bis-thiosemicarbazone 3 as a common synthetic scaffold, with two series of hydrazonoyl halides derivatives 4a-e and 7a-d. The chelation ability of these novel bis-dihydrazothiazole derivatives to perform as neutral tridentate ligands and coordinate to transition metal ions; Fe(III), Co(II), or Zn(II) through azomethine-N, thiazole-S, and azo-N atoms to form metal complexes with a metal/ligand ratio of 2:1 was elucidated. Diffused reflectance, magnetic moment, 1HNMR, FT-IR, TGA, and molar conductivity, were used to interpret the structures of all new xylenyl-spaced bis-heterocyclic compounds and their metal chelates. In-vitro, antibacterial and antiviral screening of these innovative xylenyl-spaced bis-dihydrazothiazole derivatives, as well as a selected group of their transition metal chelate complexes [M2L], were inspected, and the data was evaluated in comparison to those of Ketoconazole and Gentamycin as antimicrobial control standards using the agar well diffusion assay protocol against a selected group of fungal and bacterial species. Several compounds displayed respectable to great antimicrobial behavior against the examined microbial species. Bis-dihydrazothiazole 6c, particularly, showed exceptional inhibition of both C. albicans and E. coli. However, bis-dihydrazothiazolone 9b showed excellent inhibition of A. fumigatus. Additionally, amongst the three synthesized metal complexes [M2L], only the zinc complex, [Zn2L] showed remarkable inhibition of both C. albicans and S. typhimurium and was even more potent than the free ligand, 9a itself.

Synthesis, Characterization and Biological Activity of Fe(II), Cu(II), and Cd(II) with Schiff Base Ligands (SBLs): Biological Screening of Divalent Metal Chelated Complex

This study aimed to develop novel Schiff base ligands (SBLs), namely N1,N2-Bis(4-nitrobenzylidene)benzene-1,2-diamine (1), 4,6-Dimethyl-N-((5-nitrofuran-2-yl)methylene)pyrimidin-2-amine (2) and N1,N2-Bis((5-nitrofuran-2-yl)methylene)benzene-1,2-diamine (3). It also aimed to examine how they coordinate with various bidentate transition metal ions to form metal complexes. The goal was to properly characterize the newly synthesized chemicals and investigate their possible uses in chemical and pharmaceutical industries, with an emphasis on the drug industry. Thin-layer chromatography (TLC) was used to methodically monitor and confirm the synthesis process at each step. The compounds were then put through characterization procedures such as Fourier transform infrared spectroscopy (FTIR), urease inhibition assays, and assessments of antioxidant activity.

Cover Feature: AcSac, SacSac, and SacNac, the Forgotten Sulfur‐Based Ligands and their Reactivity in the Formation of Main and Transition Metal Complexes (Eur. J. Inorg. Chem. 19/2024)

Cover Feature: AcSac, SacSac, and SacNac, the Forgotten Sulfur‐Based Ligands and their Reactivity in the Formation of Main and Transition Metal Complexes (Eur. J. Inorg. Chem. 19/2024)

Theoretical Analysis of Coordination Geometries in Transition Metal-Histidine Complexes Using Quantum Chemical Calculations.

A theoretical investigation utilizing density functional theory (DFT) calculations was conducted to explore the coordination complexes formed between histidine (His) ligands and various divalent transition metal ions (Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+). Conformational exploration of the His ligand was initially performed to assess its stability upon coordination. Both 1:1 and 1:2 of metal-to-ligand complexes were scrutinized to elucidate their structural features and the relative stability of the complexes. This study examined the ability of His to act as a bidentate or tridentate coordinating ligand, along with the differences in coordination geometry when solvent effects were incorporated. The reduced density gradient (RDG) analysis and local electron attachment energy (LEAE) analysis were employed to elucidate the interaction planes and the nucleophilic and electrophilic properties. The electronic properties were analyzed through electrostatic potential (ESP) maps and natural population analysis (NPA) of atomic charge distributions. This computational study provides valuable insights into the diverse coordination modes of His and its interactions with divalent transition metal ions, contributing to a better understanding of the role of this amino acid ligand in the formation of transition metal complexes. The findings can aid in the design and construction of self-assembled structures involving His-metal coordination.

Metronidazole Interaction with Cu2+ and Zn2+: Speciation Study in Aqueous Solution and Biological Activity Evaluation.

Metronidazole (2-methyl-5-nitro-1H-imidazole-1-ethanol, MNZ) is a well-known and widely used drug for its excellent activity against various anaerobic bacteria and protozoa. The purpose of this study is to elucidate the ability of MNZ to form metal complexes with Cu2+ and Zn2+ and to demonstrate that complexation increases its bioactivity profile against different pathogenic microorganisms. The interaction of MNZ with Cu2+ and Zn2+ was investigated in NaCl aqueous solution under different conditions of temperature (15, 25, and 37 °C) and ionic strength (0.15, 0.5, and 1 mol L-1) by potentiometric and spectrophotometric titrations. The obtained speciation models include two species for the Cu2+-containing system, namely, CuL and CuL2, and three species for the Zn2+-containing system, namely, ZnLH, ZnL, and ZnLOH. The formation constants of the species were calculated and their dependence on temperature and ionic strength evaluated. Comparison of the sequestering ability of MNZ under physiological conditions revealed a capacity toward Cu2+ higher than that toward Zn2+. A simulation under the same conditions also showed a significant percentage of the Cu2+-MNZ species. The biological assessments highlighted that the complexation of MNZ with Cu2+ has a relevant impact on the potency of the drug against two Trypanosoma spp. (i.e., T. b. brucei and T. b. rhodesiense) and one gram-(-) bacterial species (i.e., Escherichia coli). It is noteworthy that the increased potency upon complexation with Cu2+ did not result in cytotoxicity against MRC-5 human fetal lung fibroblasts and primary peritoneal mouse macrophages.

Porphyrin nanoparticles-based portable smartphone platform for visual monitoring heavy metal Cr (Ⅲ) in the environment

Chromium ions exist in various valence states in the environment, and their pollution poses serious harm to social ecology and human health. The existing detection is mostly focused on Cr6+, while the detection related to Cr3+ is often overlooked. Cr3+ has a certain impact on soil, water, and the growth of animals and plants and even disrupts ecological balance. Accordingly, it is necessary to explore sensitive, convenient, and fast detection devices for Cr3+ in the environment. Here, we have designed a ratio fluorescence probe with porphyrin nanoparticles formed by block copolymers as the sensing core for ultra sensitive detection of Cr3+. The porphyrin nanoparticles can effectively bind with Cr3+ to form metal complexes, leading to ligand metal charge transfer (LMCT), which will result in a significant color change of the probe from red to blue. Furthermore, we have developed two portable fluorescence sensors for Cr3+ in soil and water, respectively. These portable sensing platforms based on designed nanoprobes and smartphones can convert the color information of fluorescent photos into digital information for real-time analysis. Thus, the method reported in this article can provide a possibility for rapid on-site and visual inspection of Cr3+ in soil and water from different regions.

Extraction and characterization of anthocyanin pigments from Iris flowers and metal complex formation

Exploring the chemical processes and factors influencing the stability of the blue color derived from anthocyanins is a crucial objective in agricultural and food chemistry research. The ability of these compounds to bind with metals could potentially stabilize anthocyanins extracted from plant-based foods or enable modifying their hues for application as natural food colorants. This study had two core objectives - first, to extract and identify the major anthocyanin pigments responsible for iris flower coloration. Second, to selectively complex purified iris anthocyanins with aluminum (Al3+) and copper (Cu2+) ions, probing the coordination chemistry underlying synthetic metalloanthocyanin formation. Fresh iris flowers were collected and anthocyanins extracted using an optimized acidic solution. After separation, anthocyanins were complexed with metals Al3+ and Cu2+ at pH 5–6 to understand better the evolution of blue and green colors in anthocyanin-metal chelates. Characterization of anthocyanins and their metal complexes utilized UV–visible spectrometry, colorimetry (L\\* a\\*b\\* values), FTIR spectroscopy, and LC-MS. Metal complexation of anthocyanins exhibited bathochromic shifts of visible absorption maxima from 538 to 584 nm for Al-complex and 538–700 nm for Cu-complex. Color changes were accompanied by decreased lightness (L\\*, from 87 to 81) and color coefficients a\\* (+5.4 to −6.8) and b\\* (−12.2 to −4.8). LC-MS analysis identified five major anthocyanin aglycones: cyanidin (Cyd, m/z 289), delphinidin (Dpd, m/z 305), petunidin (Ptd, m/z 229), malvidin (Mv, m/z 329) and pelargonidin (m/z 273), along with various glycosylated derivatives. This work successfully isolated key iris anthocyanin pigments and elucidated their metal chelation interactions underlying expanded floral color production, bridging knowledge gaps about this underexplored genus.

AcSac, SacSac, and SacNac, the Forgotten Sulfur‐Based Ligands and their Reactivity in the Formation of Main and Transition Metal Complexes

AcAc (β‐acetylacetonate) are among the first ligands ever, to be studied. They all form stable complexes with most metals. During the 1960s, their sulfur derivatives were introduced; AcSac (β‐thioketonate), SacSac (β‐dithioketonate) and SacNac (β‐thioketoiminate). These derivatives were conferred contrasting reactivity, stereochemical, magnetic and spectral properties to their formed complexes. Later, sulfur‐ligands were at their pinnacle in the early 1970s, but their fall into disuse was due to the lack of methodologies for obtaining them and the lack of synthetic tools for their structural modification. As an effort to promote the study and application of these sulfur‐ligands; this review will address its history, the properties they bring to the metal centers and their potential applications.