Water Ligands Research Articles

Antimonotungstate-Based Heterometallic Framework Formed by the Synergistic Strategy of In Situ-Generated Krebs-Type Building Units and the Substitution Reaction and Its High-Efficiency Biosensing KRAS Gene.

A novel antimonotungstate (AT)-based heterometallic framework {[Er(H2O)6]2[Fe4(H2pdc)4(B-β-SbW9O33)2]}·50H2O (1, H2pdc = pyridine-2,5-dicarboxylic acid) was obtained through a synergistic strategy of in situ-generated transition-metal-encapsulated polyoxometalate (POM) building units and the substitution reaction. Its structural unit is composed of a tetra-FeIII-substituted Krebs-type [Fe4(H2pdc)4(B-β-SbW9O33)2]6- subunit and two [Er(H2O)6]3+ cations. This subunit can be regarded as a product of carboxylic oxygen atoms of H2pdc ligands replacing active water ligands in the [Fe4(H2O)10(B-β-SbW9O33)2]6- species. Apparently, the substitution action of carboxylic oxygen atoms of H2pdc ligands for active water ligands, together with the coordination function of Er3+ ions, plays a connection role in the architecture of the three-dimensional (3-D) heterometallic framework. Based on the stability and high redox activity of 1, a glassy carbon electrode modified by 1 is used for the construction of an electrochemical biosensor (ECBS). Thus, such 1-based ECBS can sensitively detect the KRAS gene (a key genetic marker for identifying the occurrence of malignant tumors) and displays a low detection limit (0.106 pM), high selectivity, and reproducibility. This work not only provides a feasible approach to prepare novel multicomponent POM-based heterometallic frameworks but also establishes a new platform for biosensing the KRAS gene and extends the application scope of POM-based functional materials.

Secondary sphere interactions modulate peroxynitrite scavenging by the E2 domain of amyloid precursor protein.

Peroxynitrite (ONOO-) is a highly reactive nitrogen species that can cause significant damage to proteins, lipids, and DNA. Various enzymes, including metalloenzymes, play crucial roles in reducing ONOO- concentrations to protect cellular components. While the interaction of ONOO- with heme proteins is well known, the reduction by Cu-containing proteins is less studied. Amyloid precursor protein (APP), implicated in Alzheimer's disease, has an E2 domain that binds copper ions with a dissociation constant of KD ∼ 10-12 M and is proposed to be involved in iron homeostasis, copper trafficking, and oxidative stress response. Our recent studies using EXAFS, UV-Vis, and EPR spectroscopy revealed a previously unidentified labile water ligand in the Cu(II) site of the E2 domain, suggesting reactivity with anionic substrates like ONOO-. Experimental data showed that Cu(I)-E2 reduces ONOO- at a significant rate (1.1 × 105 M-1 s-1), comparable to native peroxynitrite scavengers, while maintaining active site integrity through multiple redox cycles. This study further investigates the mechanism of ONOO- reduction by Cu(I)-E2 using the Griess assay, demonstrating that reduction occurs via single electron transfer, forming nitrite and nitrate. This process aligns with previous findings that Cu(I)-E2 is oxidized to Cu(II)-E2 upon ONOO- reduction. Mutations at Lys435, affecting secondary sphere interactions, revealed that factors beyond electrostatics are involved in substrate recruitment. MD simulations suggest that steric hindrance from a newly formed hydrogen bond also plays a role. Understanding ONOO- reduction by the E2 domain of APP expands our knowledge of copper proteins in mitigating oxidative stress and elucidates their physiological and pathological roles, particularly in Alzheimer's disease.

Shielding Fluoride Ion Basicity through Diurea Coordination for Nonaqueous Fluoride Shuttle Batteries

AbstractThe strong basicity of fluoride ions leads to detrimental nucleophilic attack on organic components in the electrolytes, such as β‐hydrogen elimination reactions with organic cations and solvents, converting “naked” F− into corrosive and unstable bifluoride (HF2−) ions. These reactions significantly constrain the choice of suitable solvents and salts to develop electro(chemical) stable fluoride ion electrolytes. In this work, we replaced the triple water ligands typically present in industrial organic fluoride salts with dual 1,3‐diphenylurea (DPU) coordination via hydrogen bonding interaction. This modification successfully suppressed the Lewis basicity of fluoride ions, providing long‐term chemical stability (over 1000 hours) across a wide range of aprotic solvents, a broadened electrochemical stability window (−2.5–0.9 V vs. Ag+/Ag) and high ionic conductivity (1.7 mS cm−1) at room temperature. Additionally, the weaker hydrogen bonding in F−‐DPU coordination, compared to the conventional boron‐based anion acceptor (AA) strategy that relies on intensive Lewis acid‐base interactions, facilitates faster (de)fluorination kinetics at the electrode. The proposed room temperature fluoride ion batteries sustain improved electrochemical performance by pairing with the Pb‐PbF2 anode and BiF3 or Ag cathode.

Shielding Fluoride Ion Basicity through Diurea Coordination for Nonaqueous Fluoride Shuttle Batteries.

The strong basicity of fluoride ions leads to detrimental nucleophilic attack on organic components in the electrolytes, such as β-hydrogen elimination reactions with organic cations and solvents, converting "naked" F- into corrosive and unstable bifluoride (HF2 -) ions. These reactions significantly constrain the choice of suitable solvents and salts to develop electro(chemical) stable fluoride ion electrolytes. In this work, we replaced the triple water ligands typically present in industrial organic fluoride salts with dual 1,3-diphenylurea (DPU) coordination via hydrogen bonding interaction. This modification successfully suppressed the Lewis basicity of fluoride ions, providing long-term chemical stability (over 1000 hours) across a wide range of aprotic solvents, a broadened electrochemical stability window (-2.5-0.9 V vs. Ag+/Ag) and high ionic conductivity (1.7 mS cm-1) at room temperature. Additionally, the weaker hydrogen bonding in F--DPU coordination, compared to the conventional boron-based anion acceptor (AA) strategy that relies on intensive Lewis acid-base interactions, facilitates faster (de)fluorination kinetics at the electrode. The proposed room temperature fluoride ion batteries sustain improved electrochemical performance by pairing with the Pb-PbF2 anode and BiF3 or Ag cathode.

Linear free energy relationship modelling for predicting metal-ligand stability constants by thermodynamic radii

ABSTRACT The thermodynamic radii of 15 metal ions Ag+, Al3+, Am3+, Ba2+, Be2+, Fe3+, Ga3+, Hg2+, In3+, K+, Li+, Na+, NpO2 +, Sr2+, and UO2 2+ were calculated by linear free energy relationship modelling using 8269 experimental stability constants (logK) of ML complexes of 42 metal ions (M) and 1990 diverse organic ligands (L) in water. The predictive performance of relationships on the base of the thermodynamic radii was estimated on 5272 combinations of ligands and metal ion pairs of external test sets. Squared determination coefficient ( R d e t 2 ) and root mean squared error (RMSE) of logK predictions are 0.801 and 2.4 for combined data of the test sets, respectively. The corresponding performances for the 3003 combinations of training data are R d e t 2 0.921 and RMSE 1.7.

Crystal structure of [Ni(OH2)6]Cl2·(18-crown-6)2·2H2O.

The crystal structure of the title compound, hexa-aqua-nickel(II) dichloride-1,4,7,10,13,16-hexa-oxa-cyclo-octa-deca-ne-water (1/2/2), [Ni(H2O)6]Cl2·2C12H24O6·2H2O, is reported. The asymmetric unit contains half of the Ni(OH2)6 moiety with a formula of C12H32ClNi0.50O10 at 105 K and triclinic (P1) symmetry. The [Ni(OH2)6]2+ cation has close to ideal octa-hedral geometry with O-Ni-O bond angles that are within 3° of idealized values. The supra-molecular structure includes hydrogen bonding between the water ligands, 18-crown-6 mol-ecules, Cl- anions, and co-crystallized water solvent. Two crown ether mol-ecules flank the [Ni(OH2)6]2+ mol-ecule at the axial positions in a sandwich-like structure. The relatively symmetric hydrogen-bonding network is enabled by small Cl- counter-ions and likely influences the more idealized octa-hedral geometry of [Ni(OH2)6]2+.

Chemistry of Formate and Water Ligands on Metal Oxide Cluster Nodes of Metal-Organic Framework hcp Hf-UiO-66: Keys to Understanding Reactivity of Paired μ2-OH and Defect Sites.

Many metal-organic frameworks (MOFs) incorporate nodes that are metal oxide clusters, and ligands that have been observed on these nodes include formates, acetates, water, hydroxyl groups, and others, all of which are potentially important in affecting reactivities for applications in separations, catalysis, and sensing. Formate is a common node ligand, arising from formic acid used as a modulator and from N,N-dimethylformamide used as a solvent in MOF syntheses. Yet only little work has been reported characterizing the reactivities of node formate ligands. Infrared spectra reported here show that formate bonds to two types of sites on the paired Hf6O8 nodes of hcp UiO-66, namely, defect and μ2-OH sites. Quantifying the number of formate ligands by 1H NMR spectroscopy of digested samples showed an almost equal number of formate ligands on the two sites, indicating the likelihood that they neighbor each other. These formate ligands interact with water molecules, reversibly switching their bonding from bidentate to monodentate. The formates on μ2-OH sites of hcp Hf-UiO-66 interact much more strongly with water than those on defect sites of the same node, and both interact more strongly than isolated defect sites of Hf-UiO-66. Correspondingly, the catalytic activities of hcp UiO-66 determined as turnover frequencies on each site are approximately twofold higher than those on UiO-66, bolstering the inference that methanol dehydration is catalyzed by a node defect site and a neighboring node μ2-OH site. The results show how MOFs, with their well-defined node structures, provide unprecedented opportunities to understand details of reactivities and catalysis on metal oxide clusters, in contrast to bulk metal oxide surfaces.

Tailoring the Oxidizing Intermediate in the Fenton Reaction, OH⋅ or FeIV=Oaq, by Modifying the pKa of the (H2O)5FeII(H2O2) Complex, and the Case of PDS - a DFT Study.

A DFT analysis of the Fenton and Fenton-like reactions points out that the pH effect on the nature of the oxidizing intermediate formed is due to a pKa of the peroxide when hydroperoxides are used. When S2O8 2- is used, the pH effect is due to the pKa of one of the water ligands of the central iron cation. The results suggest that the choice of the hydroperoxide and the ligands present affects the pH at which the transition from the formation of hydroxyl radicals to the formation of FeIV=Oaq occurs.

Intermediate Formation via Proton Release during the Photoassembly of the Water-Oxidizing Mn4CaO5 Cluster in Photosystem II.

The early stages of the photoassembly of the water-oxidizing Mn4CaO5 cluster in spinach photosystem II (PSII) were monitored using rapid-scan time-resolved Fourier transform infrared (FTIR) spectroscopy. Carboxylate stretching and the amide I bands, which appeared upon the flash-induced oxidation of a Mn2+ ion, changed their features during the subsequent dark rearrangement process, indicating the relocation of the Mn3+ ion concomitant with protein conformational changes. Monitoring the isotope-edited FTIR signals of a Mes buffer estimated that nearly two protons are released upon the Mn2+ oxidation. Quantum chemical calculations for models of the Mn binding site suggested that the proton of a water ligand is transferred to D1-H332 through a hydrogen bond upon the Mn3+ formation and then released to the bulk as the Mn3+ shifts to bind to this histidine. Another Mn2+ ion may be inserted to form a binuclear Mn3+Mn2+ complex, whose structure was calculated to be stabilized by a μ-hydroxo bridge hydrogen-bonded with deprotonated D1-H337. Nearly one additional proton can thus be released from this histidine, assuming that it is mostly protonated before illumination. Alternatively, a proton could be released by further insertion of Ca2+, forming a Mn3+Mn2+Ca2+ complex with another hydroxo ligand connecting Ca2+ to the Mn3+Mn2+ complex.

Reframing microplastics as a ligand for metals reveals that water quality characteristics govern the association of cadmium to polyethylene

Environmental characteristics including water quality and sediment properties alter the hazard that metals pose to aquatic systems by governing the speciation and partitioning of metals between water, sediment, and biotic ligands; however, alternate ligands are being introduced into aquatic systems through anthropogenic activity. Microplastics are a ligand on which metals interact through adsorption to the plastic surface. It remains unknown what factors determine the amount of metal bound to microplastic. Using a combination of laboratory experiments and machine learning, we tested a suite of eighteen environmental parameters (inclusive of both water and sediment) to understand how they influence association of cadmium to a representative microplastic, polyethylene. From this, we developed and tested a predictive model that outlines the characteristics that favour the association of cadmium to microplastic. Alkalinity, humification index of dissolved organic matter, and pH (all of which are water quality characteristics) were the three factors determining the proportion of cadmium adsorbed to plastics. These results align with other predictive models, such as the Biotic Ligand Model in demonstrating the governance of metal behaviour by water quality characteristics. To assess the relationship of the amount of cadmium bound to microplastic and cadmium uptake, an exposure was completed in which fathead minnows (Pimephales promelas) were acclimated to environments representing each of the potential outcomes of the model. The uptake of cadmium was not significantly different between groups, indicating that the stress of alterations to water quality may be a confounding factor in determining the exposure risk of microplastics and cadmium.

Active Site Characterization of a Campylobacter jejuni Nitrate Reductase Variant Provides Insight into the Enzyme Mechanism.

Mo K-edge X-ray absorption spectroscopy (XAS) is used to probe the structure of wild-type Campylobacter jejuni nitrate reductase NapA and the C176A variant. The results of extended X-ray absorption fine structure (EXAFS) experiments on wt NapA support an oxidized Mo(VI) hexacoordinate active site coordinated by a single terminal oxo donor, four sulfur atoms from two separate pyranopterin dithiolene ligands, and an additional S atom from a conserved cysteine amino acid residue. We found no evidence of a terminal sulfido ligand in wt NapA. EXAFS analysis shows the C176A active site to be a 6-coordinate structure, and this is supported by EPR studies on C176A and small molecule analogs of Mo(V) enzyme forms. The SCys is replaced by a hydroxide or water ligand in C176A, and we find no evidence of a coordinated sulfhydryl (SH) ligand. Kinetic studies show that this variant has completely lost its catalytic activity toward nitrate. Taken together, the results support a critical role for the conserved C176 in catalysis and an oxygen atom transfer mechanism for the catalytic reduction of nitrate to nitrite that does not employ a terminal sulfido ligand in the catalytic cycle.

Structure of Aquifex aeolicus lumazine synthase by cryo-electron microscopy to 1.42 Å resolution.

Single-particle cryo-electron microscopy (cryo-EM) has become an essential structural determination technique with recent hardware developments making it possible to reach atomic resolution, at which individual atoms, including hydrogen atoms, can be resolved. In this study, we used the enzyme involved in the penultimate step of riboflavin biosynthesis as a test specimen to benchmark a recently installed microscope and determine if other protein complexes could reach a resolution of 1.5 Å or better, which so far has only been achieved for the iron carrier ferritin. Using state-of-the-art microscope and detector hardware as well as the latest software techniques to overcome microscope and sample limitations, a 1.42 Å map of Aquifex aeolicus lumazine synthase (AaLS) was obtained from a 48 h microscope session. In addition to water molecules and ligands involved in the function of AaLS, we can observe positive density for ∼50% of the hydrogen atoms. A small improvement in the resolution was achieved by Ewald sphere correction which was expected to limit the resolution to ∼1.5 Å for a molecule of this diameter. Our study confirms that other protein complexes can be solved to near-atomic resolution. Future improvements in specimen preparation and protein complex stabilization may allow more flexible macromolecules to reach this level of resolution and should become a priority of study in the field.

Crystal Structure and Hirshfeld Surface Analysis of a Heterometallic Hofmann-Type-Like Compound

In this study; a new heterometallic compound defined by the open formula [Cd(H2O)2Ni(CN)4]4[Cd(H2O)4Ni(CN)4]5 was synthesized in crystal form. Consisting of components such as water molecules, [Ni(CN)4]2− anions, and cadmium transition metal atoms, this new crystal structure has no analogues which might have been previously obtained, even with other transition metal atoms. It is a new compound and a unique example of a crystal. The structural properties of this heterometallic compound have been characterized by single crystal X-ray diffraction spectroscopy (SC-XRD), FT-IR spectroscopy, thermal analysis and elemental analysis methods. According to the data obtained from the SC-XRD technique, this heterometallic compound has a monoclinic crystal system and a C2/c space group. The asymmetric unit of this compound consists of five Cd(II) ions, five Ni(II) ions, eighteen cyanide ligands, and fourteen coordinated water ligand molecules. In addition, theoretical calculations have been made with the Gaussian 03 program in order to obtain more information about this heterometallic Hofmann-type-like compound. The chemical properties of this new compound have been calculated using its HOMO and LUMO values and the natural bond orbital (NBO) analyses. In addition, Hirshfeld surface analysis of the asymmetric unit of this compound has been performed with the CrystalExplorer program. As a result of the Hirshfeld surface analysis, extensive information has been obtained about the weak intramolecular and intermolecular forces that form this new crystalline compound.

Hydration energies of calcium hydroxide cation, CaOH+(H2O)x (x = 1–6), studied using guided ion beam tandem mass spectrometry

Hydration energies of CaOH+(H2O)x, x = 1–6, were obtained using threshold collision-induced dissociation (TCID) with xenon (Xe) as conducted with a guided ion beam tandem mass spectrometer (GIBMS). The primary reaction pathway observed for all complexes is the loss of one water ligand, followed by the loss of additional water molecules at higher collision energies for x > 1. The kinetic-energy-dependent cross sections for dissociation of CaOH+(H2O)x complexes were modeled to obtain 0 K binding energies after accounting for lifetime effects, energy distributions, and pressure effects. Except for x = 5, experimental threshold energies measured through TCID agree well with theoretical hydration energies determined using B3LYP/6-311+G(d,p) structure geometries followed by single point energies calculated at B3LYP, B3P86, M06, and MP2(full) levels of theory with a 6-311+G(2d,2p) basis set. B3LYP-GD3BJ and ωB97XD calculations were also used, with the former yielding results having the best agreement with the threshold energies extracted from the analysis of the TCID cross sections.

High Selectivity in Csp2-Csp2 versus Csp3-O Reductive Elimination from Cycloplatinated(IV) Complexes.

The cycloplatinated(IV) complexes trans-[Pt(p-MeC6H4)(C∧N)(OAc)2(H2O)] (C∧N = benzo[h]quinolate, bhq, 2a, and 2-phenylpyridinate, ppy, 2b) were prepared by reacting the corresponding [Pt(p-MeC6H4)(C∧N)(SMe2)] precursors with PhI(OAc)2 through an oxidative addition (OA) reaction. Thermolysis of 2a at 65 °C generates cis-[Pt(κ1N-10-(p-MeC6H4)-bhq)(OAc)2(H2O)], 3a, which is the product of a Csp2Ar-Csp2bhq reductive elimination (RE). The observed coupling reaction is significantly different from the previously reported analogous thermolysis of trans-[PtMe(C∧N)(OAc)2(H2O)] (C∧N = bhq, 2c, and ppy, 2d) that selectively releases Me-OAc (C-O RE). The density functional theory (DFT) calculations and experimental observations reveal that the Csp2Ar-Csp2bhq coupling reaction occurs through the dissociation of a coordinated water ligand. This in turn is followed by the concomitant bond forming and bond breaking process via a three-center ring transition state, in contrast to the Csp3Me-OAc coupling, which had taken place by an outer sphere SN2 type RE reaction in methyl complexes.

Illuminating tetracycline: The role of metal coordination in fluorescence emission and its optical detection potential

Rapid on-site detection of antibiotics such as tetracycline (TC) is crucial for understanding their elusive environmental fate. Fluorescence-based strategies are promising owing to their sensitivity and ease of use. This study demonstrates that Al3+–TC coordination significantly enhances the intrinsic fluorescence of TC at excitation/emission wavelengths of 395/490 and 270/490 nm. The fluorescence emission intensity is proportional to the TC concentration between 0.005 and 7.5 μmol/L TC, which increases the detection sensitivity by 40 times compared with the commonly used absorption signals. Density functional theory calculations, when combined with the independent gradient model, indicate that the six-membered chelate ring in the octahedral Al3+–TC complex restricts molecular motion, along with two intramolecular hydrogen bonds formed between TC and water ligands. These factors lead to a narrowing of the energy gap between the highest occupied and lowest unoccupied molecular orbitals upon complexation with Al3+. Consequently, the enhanced molecular rigidity and facilitated electron transfer result in a significant increase in the fluorescence quantum yield. This captivating fluorescence response significantly enhances the proficiency of optical signals in detecting TC, thereby enriching future environmental monitoring systems with greater diversity and adaptability.

Water Ligands Regulate the Redox Leveling Mechanism of the Oxygen-Evolving Complex of the Photosystem II.

Understanding how water ligands regulate the conformational changes and functionality of the oxygen-evolving complex (OEC) in photosystem II (PSII) throughout the catalytic cycle of oxygen evolution remains a highly intriguing and unresolved challenge. In this study, we investigate the effect of water insertion (WI) on the redox state of the OEC by using the molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) hybrid methods. We find that water binding significantly reduces the free energy change for proton-coupled electron transfer (PCET) from Mn to YZ•, underscoring the important regulatory role of water binding, which is essential for enabling the OEC redox-leveling mechanism along the catalytic cycle. We propose a water binding mechanism in which WI is thermodynamically favored by the closed-cubane form of the OEC, with water delivery mediated by Ca2+ ligand exchange. Isomerization from the closed- to open-cubane conformation at three post-WI states highlights the importance of the location of the MnIII center in the OEC and the orientation of its Jahn-Teller axis to conformational changes of the OEC, which might be critical for the formation of the O-O bond. These findings reveal a complex interplay between conformational changes in the OEC and the ligand environment during the activation of the OEC by YZ•. Analogous regulatory effects due to water ligand binding are expected to be important for a wide range of catalysts activated by redox state transitions in aqueous environments.

To Bind or Not to Bind? A Comprehensive Characterization of TIR1 and Auxins Using Consensus In Silico Approaches

Auxins are chemical compounds of wide interest, mostly due to their role in plant metabolism and development. Synthetic auxins have been used as herbicides for more than 75 years and low toxicity in humans is one of their most advantageous features. Extensive studies of natural and synthetic auxins have been made in an effort to understand their role in plant growth. However, molecular details of the binding and recognition process are still an open question. Herein, we present a comprehensive in silico pipeline for the assessment of TIR1 ligands using several structure-based methods. Our results suggest that subtle dynamics within the binding pocket arise from water–ligand interactions. We also show that this trait distinguishes effective binders. Finally, we construct a database of putative ligands and decoy compounds, which can aid further studies focusing on synthetic auxin design. To the best of our knowledge, this study is the first of its kind focusing on TIR1.

Exploring the Deprotonation Process during Incorporation of a Ligand Water Molecule at the Dangling Mn Site in Photosystem II.

The Mn4CaO5 cluster, featuring four ligand water molecules (W1 to W4), serves as the water-splitting site in photosystem II (PSII). X-ray free electron laser (XFEL) structures exhibit an additional oxygen site (O6) adjacent to the O5 site in the fourth lowest oxidation state, S3, forming Mn4CaO6. Here, we investigate the mechanism of the second water ligand molecule at the dangling Mn (W2) as a potential incorporating species, using a quantum mechanical/molecular mechanical (QM/MM) approach. Previous QM/MM calculations demonstrated that W1 releases two protons through a low-barrier H-bond toward D1-Asp61 and subsequently releases an electron during the S2 to S3 transition, resulting in O•- at W1 and protonated D1-Asp61. During the process of Mn4CaO6 formation, O•-, rather than H2O or OH-, best reproduced the O5···O6 distance. Although the catalytic cluster with O•- at O6 is more stable than that with O•- at W1 in S3, it does not occur spontaneously due to the significantly uphill deprotonation process. Assuming O•- at W2 incorporates into the O6 site, an exergonic conversion from Mn1(III)Mn2(IV)Mn3(IV)Mn4(IV) (equivalent to the open-cubane S2 valence state) to Mn1(IV)Mn2(IV)Mn3(IV)Mn4(III) (equivalent to the closed-cubane S2 valence state) occurs. These findings provide energetic insights into the deprotonation and structural conversion events required for the Mn4CaO6 formation.

Magnetic coupling interaction-related photoluminescence behaviors in all-inorganic manganese chloride perovskites

Manganese halides, as dilute magnetic semiconductor materials, have magnetic coupling interactions that play an essential role in their photoluminescence (PL); however, such interactions remain controversial. AMnCl3 (AMC, A = K, Rb, and Cs) and their hydrates AMnCl3·2H2O (AMCH, A = K, Rb, and Cs) are both in the ABX3 configuration but exhibit a wide variety of structures with different connectivity types and dimensions. Their magnetic coupling interaction has been demonstrated. However, few studies have systematically investigated the PL in conjunction with the magnetic coupling interaction over these chloride compounds. In this paper, the effect of the magnetic coupling interaction on AMC and AMCH PL is mainly revealed by temperature-dependent PL spectra and lifetimes. The MnX6 (X6 = Cl4(H2O)2 or Cl6) cluster connection types affect the Mn2+–Mn2+ distances. The magnetic coupling interaction between MnX6 octahedrons affects the radiative transitions of manganese chlorides, which is influenced by the Mn2+–Mn2+ distance, local symmetry, and water ligand. The Mn2+–Mn2+ distance and the magnetic coupling interaction also affect their lifetimes. Variations in magnetic coupling interactions can shift emission wavelength, especially dual-emissions and near-infrared (NIR) emission at lower temperatures while A+ = K+. This work helps researchers understand the optical process of Mn2+ ions in different manganese compounds and provides new insights into the design of tailored Mn2+ ion phosphors.