Main Ligand Research Articles

Maternal obesity induces sex-specific changes in the endocannabinoid system of the hypothalamus and dorsal hippocampus of offspring associated with anxiety-like behavior in adolescent female rats

Maternal obesity during perinatal period increases the risk of metabolic and behavioral deleterious outcomes in the offspring, since it is critical for brain development, maturation, and reorganization. These processes are highly modulated by the endocannabinoid system (ECS), which comprises the main lipid ligands anandamide and 2-arachidonoylglycerol, cannabinoid receptors 1 and 2 (CB1R and CB2R), and several metabolizing enzymes. The ECS is overactivated in obesity and it contributes to the physiological activity of the hypothalamus-pituitary-adrenal (HPA) axis, promoting stress relief. We have previously demonstrated that maternal high-fat diet during gestation and lactation programmed the food preference for fat in adolescent male offspring and adult male and female offspring. In the present study, we hypothesized that maternal diet-induced obesity would induce sex-specific changes of the ECS in the hypothalamus and dorsal hippocampus of rat offspring associated with dysregulation of the HPA axis and stress-related behavior in adolescence. Rat dams were fed a control (C) or an obesogenic high-fat high-sugar diet (OD) for nine weeks prior to mating and throughout gestation and lactation. Maternal obesity differentially altered the CB1R in the hypothalamus of neonate offspring, with significant increase in male but not in female pups, associated with decreased CB2R prior to obesity development. In adolescence, maternal obesity induced anxiety-like behavior only in adolescent females which was associated with increased content of CB1R in the dorsal hippocampus. Our findings suggest that the early origins of anxiety disorders induced by maternal exposome is associated with dysregulation of the brain ECS, with females being more susceptible.

Preparation of SnO2/TiO2 composite photocatalysts using yeast and their catalytic performance

Constructing coupled semiconductor photocatalysts is an important approach to improve the photocatalytic activity of TiO[Formula: see text]. Herein, SnO[Formula: see text]/TiO[Formula: see text] composite photocatalysts were successfully synthesized through a hydrothermal method using yeast as a biological template. The as-obtained products were characterized by X-ray diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy (SEM), ultraviolet-visible spectra and nitrogen adsorption/desorption testing methods. Results showed that the nano-sized SnO[Formula: see text] particles could be solvothermally synthesized at 150–180[Formula: see text]C, and the C=O and C–O groups in the yeast were the main capping ligands of the SnO[Formula: see text] particles, playing a key role in the synthesis of SnO[Formula: see text]. SEM demonstrated that the SnO[Formula: see text]/TiO[Formula: see text] composites possessed very loose structures and good uniformity. Finally, the application experiment showed that the as-obtained SnO[Formula: see text]/TiO[Formula: see text] composites exhibited exceptional effectiveness in degrading Rhodamine B.

Synthesis, crystal structure, hirshfeld surface analysis, and computational studies of dimeric and polymeric cadmium complexes

In the current investigation, a new dimeric [Cd(DNBA)2(py)2]2 and a polymeric [Cd(DNBA)2(pyz)2]n cadmium complexes have been prepared by the reaction of 3,5-dinitrobenzoic acid (main ligand), nitrogen donor auxiliary ligands (pyridine and pyrazine), and Cd(II) sulphate in aqueous media. The crystal structures of the synthesized compounds were determined by single-crystal X-ray diffraction analysis. The crystal structures were investigated in terms of the coordination geometry, dihedral angles between various rings, and intermolecular interactions. The solid-state assembly was stabilized by various interatomic contacts, explored by Hirshfeld surface analysis. Void analysis was performed to predict the response of crystals to the applied stress. The optimized molecular geometries of the compounds were achieved utilizing the DFT approach along with the B3LYP functional/6–311G(d,p)/LANL2DZ basic set. MEP maps, molecular orbital theory, and quantum chemical parameters for the synthesized compounds were generated using the same level of theory.

Exploring CCR5 + T regulatory cell subset dysfunction in type 1 diabetes patients: implications for immune regulation.

T regulatory lymphocytes (Treg) expressing CCR5 exhibit strong suppression activity in various autoimmune disorders. However, there remains a lack of comprehensive understanding regarding their involvement in the development of type 1 diabetes (T1D). In this study, we examined the role of the CCR5/CCL5 axis in regulating inflammatory response and its impact on regulatory T cells in type 1 diabetes (T1D). We hypothesize that dysregulation of the CCR5/CCL5 axis contributes to the development and progression of T1D through modulation of Treg-dependent immune responses. We analyzed the expression levels of CCR5 on Tregs isolated from individuals with T1D, as well as the plasma concentration of its main ligands. We found that Tregs from T1D patients exhibited decreased expression of CCR5 compared to healthy controls. Additionally, we observed a correlation between the expression levels of CCR5 on Tregs and their immunosuppressive function in T1D patients. Our results indicate the impaired migratory capacity of CCR5 + Tregs, suggesting a possible link between the dysregulation of the CCR5/CCL5 axis and impaired immune regulation in T1D. In line with previous studies, our findings support the notion that dysregulation of the CCR5/CCL5 axis contributes to the development and progression of type 1 diabetes (T1D) by modulating Treg-dependent immune responses. The decreased expression of CCR5 on Tregs in T1D patients suggests a potential impairment in the migratory capacity of these cells, which could compromise their ability to suppress autoreactive T cells and maintain immune homeostasis. Furthermore, our study highlights the importance of CCR5 as a biomarker for identifying dysfunctional Tregs in T1D.

Differential Effect of Aldosterone or Mineralocorticoid Receptor Overexpression on Retinal Inflammation.

Overactivation of the mineralocorticoid receptor (MR) pathway is proinflammatory and contributes to the pathogenesis of diabetic retinopathy and of age-related macular degeneration. Excess of aldosterone, the specific MR ligand, is known to stimulate the production of proinflammatory cytokines and chemokines in extrarenal tissues and cells. In the RPE/choroid complex, aldosterone upregulated genes encoding proteins of the inflammatory response and downregulated genes encoding proteins involved in synaptic activity and neurotransmitters. Yet, cortisol, which is the main MR ligand in the eye, is a potent anti-inflammatory endogenous glucocorticoid. The aim of the present work was to better understand the role of MR activation in retinal inflammation either by acute injection of aldosterone or overexpression of the receptor. We first analyzed the retinal transcriptomic regulation induced by acute intraocular injection of aldosterone in the rat. Then, we used a transgenic rat overexpressing human MR (hMR) to also conduct retinal transcriptomic analysis as well as histological evaluation of the retina, retinal pigment epithelium and choroid. Our results show that acute intravitreal injection of aldosterone is highly proinflammatory, upregulating pathways related to microglial activation, oxidative stress, cell death, and downregulating pathways related to glial/neuronal cells activity and proper neurotransmission. On the other hand, hMR overexpression mediates a low-grade inflammation in the retina, associated with notable choroidal inflammation and choroidal neuropathy. Consequences of hMR overexpression or aldosterone-injection on retinal transcriptome reveal very distinct pathological mechanisms, with only a few common genes regulated, most of them not being regulated in the same way. Although aldosterone is highly proinflammatory in the retina, MR overactivation in its physiologic milieu mediates a low-grade inflammation in the neural retina.

Colloidal Quasi-2D Methylammonium Lead Bromide Perovskite Nanostructures with Tunable Shape and High Chemical Stability.

Control over the lateral dimensions of colloidal nanostructures is a complex task which requires a deep understanding of the formation mechanism and reactivity in the corresponding systems. As a result, it provides a well-founded insight to the physical and chemical properties of these materials. In this work, the preparation of quasi-2D methylammonium lead bromide nanostripes and discuss the influence of some specific parameters on the morphology and stability of this material is demonstrated. The variation in the amount of the main ligand dodecylamine gives a large range of structures beginning with 3D brick-like particles at low concentrations, nanostripes at elevated and ultimately nanosheets at large concentrations. The amount of the co-ligand trioctylphosphine can alter the width of the nanostripe shape to a certain degree. The thickness can be adjusted by the amount of the second precursor methylammonium bromide. Additionally, insights are given for the suggested formation mechanism of these anisotropic structures as well as for stability against moisture at ambient conditions in comparison with differently synthesized nanosheet samples.

Theoretical exploration of the photophysical properties of two series of iridium(III) complexes with different main ligand

On the basis of the thiophene-containing and furan-containing complexes, we design four complexes by introducing thiazole, isothiazole, oxazole, isoxazole on main ligands. The electronic structure, absorption and emission spectra, charge injection/transport properties, absorption and phosphorescence properties have been investigated by density functional theory (DFT) and time-dependent density functional theory (TDDFT). Introducing S atom to substitute O atom could enhance HOMO energy level, blueshift emission wavelength, decrease ΔES1- T1 value. The introduction of N atom on furan ring and thiophene ring could decrease HOMO and LUMO energy levels and energy gaps, blueshift emission wavelength, decrease ΔES1- T1 value, enhance electron transport ability. Introducing thiazole could decrease hole injection ability and ΔES1- T1, and then may have higher ΦPL. Isoxazole and isothiazole groups could facilitate the electron transition from HOMO to LUMO and enhance hole injection ability. Thiazole and isothiazole groups could increase absorption peak strength and hole transport ability.

Monolayer calcium-doped layered yttrium hydroxide adsorbent for rapid and efficient removal of fluoride from industrial wastewater

Strategies for the rapid and efficient removal of fluoridated industrial wastewater are currently lacking. Herein, monolayer calcium-doped layered yttrium hydroxide (Ca-Y LRH) was synthesized through formamide exfoliation, and its removal of fluoride reached equilibrium within 4 min. The adsorption kinetics fit the pseudo-second-order kinetic model with a faster adsorption rate (KF = 0.22 mg g−1 min−1), and the adsorption isotherm followed the Langmuir model with a maximum adsorption capacity of 483.33 mg g−1. The interlayer chloride ions in the monolayer Ca-Y LRH were the main ligands for substituting fluoride, which inhibited the increase in pH and maintained the continuation of the fluoride removal process. Furthermore, the optimum fluoride removal performance of monolayer Ca-Y LRH was predicted by software-based multiparameter methods and was found to be useful for treating fluoridated industrial wastewater samples (858.17 or 8.72 mg L−1). These findings provide novel insights into the treatment of fluoridated industrial wastewater.

Lack of membrane sex steroid receptors for mediating rapid endocrine responses in molluscan nervous systems.

Despite the lack of endogenous synthesis and relevant nuclear receptors, several papers have been published over the decades claiming that the physiology of mollusks is affected by natural and synthetic sex steroids. With scant evidence for the existence of functional steroid nuclear receptors in mollusks, some scientists have speculated that the effects of steroids might be mediated via membrane receptors (i.e. via non-genomic/non-classical actions) -a mechanism that has been well-characterized in vertebrates. However, no study has yet investigated the ligand-binding ability of such receptor candidates in mollusks. The aim of the present study was to further trace the evolution of the endocrine system by investigating the presence of functional membrane sex steroid receptors in a mollusk, the great pond snail (Lymnaea stagnalis). We detected sequences homologous to the known vertebrate membrane sex steroid receptors in the Lymnaea transcriptome and genome data: G protein-coupled estrogen receptor-1 (GPER1); membrane progestin receptors (mPRs); G protein-coupled receptor family C group 6 member A (GPRC6A); and Zrt- and Irt-like protein 9 (ZIP9). Sequence analyses, including conserved domain analysis, phylogenetics, and transmembrane domain prediction, indicated that the mPR and ZIP9 candidates appeared to be homologs, while the GPER1 and GPRC6A candidates seemed to be non-orthologous receptors. All candidates transiently transfected into HEK293MSR cells were found to be localized at the plasma membrane, confirming that they function as membrane receptors. However, the signaling assays revealed that none of the candidates interacted with the main vertebrate steroid ligands. Our findings strongly suggest that functional membrane sex steroid receptors which would be homologous to the vertebrate ones are not present in Lymnaea. Although further experiments are required on other molluscan model species as well, we propose that both classical and non-classical sex steroid signaling for endocrine responses are specific to chordates, confirming that molluscan and vertebrate endocrine systems are fundamentally different.

Synthesis, spectral elucidation and DNA binding studies of cadmium(II) carboxylates with nitrogen donor heteroligands

A new series of novel homoleptic and heteroleptic Cd(II) complexes using cyclopropanecarboxylic acid (HL1) and cyclopentanecarboxylic acid (HL2) as main ligands and N-donor species like 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), and 2,9-dimethyl-1,10-phenanthroline (Me2phen) as co-ligands were prepared and characterized by FT-IR, multinuclear (1H and 13C) NMR, and UV–Visible spectroscopies. Furthermore, the crystal structure of the Cd(II) complex coordinated by cyclopentanecarboxylic acid (HL2) and 1,10-phenanthroline (phen) was explored by single crystal X-ray diffraction (SC-XRD) analysis. The crystal structure was binuclear, in which the coordination geometry around each cadmium center was distorted pentagonal bipyramidal coordination geometry. Various intermolecular interactions were accountable for stabilizing the supramolecular associations, which were seen by Hirshfeld surface analysis in terms of interatomic contacts. The spectroanalytical data of the synthesized complexes confirm the absence of the –OH band in the spectra of complexes as compared to the spectra of the free ligands, which favour the formation of complexes. The nature of complex-DNA interaction and the effect of the coordination of heteroligands on the binding strength of complexes were probed through UV–Visible spectroscopy and cyclic voltammetry. The obtained data confirm that the interaction of DNA with the complexes is dual: intercalation as well as groove binding. The DNA binding constants (Kb) and Gibb’s free energy changes (ΔG) were also determined for these complexes. This study aims to project effective drugs with the least harmful effects that could be useful for mankind against dreadful diseases.

Female-Biased Odorant Receptor MmedOR48 in the Parasitoid Microplitis mediator Broadly Tunes to Plant Volatiles.

Odorant receptors (ORs) play a crucial role in insect chemoreception. Here, a female-biased odorant receptor MmedOR48 in parasitoid Microplitis mediator was fully functionally characterized. The qPCR analysis suggested that the expression level of MmedOR48 increased significantly after adult emergence and was expressed much more in the antennae. Moreover, an in situ hybridization assay showed MmedOR48 was extensively located in the olfactory sensory neurons. In two-electrode voltage clamp recordings, recombinant MmedOR48 was broadly tuned to 23 kinds of volatiles, among which five plant aldehyde volatiles excited the strongest current recording values. Subsequent molecular docking analysis coupled with site-directed mutagenesis demonstrated that key amino acid residues Thr142, Gln80, Gln282, and Thr312 together formed the binding site in the active pocket for the typical aldehyde ligands. Furthermore, ligands of MmedOR48 could stimulate electrophysiological activities in female adults of the M. mediator. The main aldehyde ligand, nonanal, aroused significant behavioral preference of M. mediator in females than in males. These findings suggest that MmedOR48 may be involved in the recognition of plant volatiles in M. mediator, which provides valuable insight into understanding the olfactory mechanisms of parasitoids.

Effects of Modulating BMP9, BMPR2, and AQP1 on BMP Signaling in Human Pulmonary Microvascular Endothelial Cells.

Pulmonary arterial hypertension (PAH) is a chronic disease characterized by a progressive increase in mean pulmonary arterial pressure. Mutations in the BMPR2 and AQP1 genes have been described in familial PAH. The bone morphogenetic proteins BMP9 and BMP10 bind with high affinity to BMPR2. Administration of BMP9 has been proposed as a potential therapeutic strategy against PAH, although recent conflicting evidence dispute the effect of such a practice. Considering the involvement of the above molecules in PAH onset, progression, and therapeutic value, we examined the effects of modulation of BMP9, BMPR2, and AQP1 on BMP9, BMP10, BMPR2, AQP1, and TGFB1 expression in human pulmonary microvascular endothelial cells in vitro. Our results demonstrated that silencing the BMPR2 gene resulted in increased expression of its two main ligands, namely BMP9 and BMP10. Exogenous administration of BMP9 caused the return of BMP10 to basal levels, while it restored the decreased AQP1 protein levels and the decreased TGFB1 mRNA and protein expression levels caused by BMPR2 silencing. Moreover, AQP1 gene silencing also resulted in increased expression of BMP9 and BMP10. Our results might possibly imply that the effect of exogenously administered BMP9 on molecules participating in the BMP signaling pathway could depend on the expression levels of BMPR2. Taken together, these results may provide insight into the highly complex interactions of the BMP signaling pathway.

Design and photophysical characterization of dinuclear lanthanide complexes incorporating spacer ligands along with their mononuclear analogues: A comparative study

Two heteroleptic homo-dinuclear complexes of Dy(III) and Sm(III) with pyrazine (pyz) as spacer ligand [Ln(TFPB)3(μ-pyz)Ln(TFPB)3], along with their mononuclear analogue [Ln(TFPB)3(pyz)2] were synthesized and characterized. Diketone TFPB (4,4,4-trifluoro-1-phenyl-1,3-butanedione) was incorporated as main ligand. NMR analysis depicted single peak for pyz protons for dinuclear complexes and two for mononuclear ones, which confirmed the bridging nature of pyz in former complexes. UV spectra revealed two absorption bands despite of the different metal ion and nuclearity of complex, suggesting the absorption of UV-radiation by coordinated moieties inspite of the metal ion involved. The emission spectra exhibited significant intensity of yellow and orange-red peaks for Dy(III) and Sm(III) complexes, respectively, indicating effective sensitization of metal center. The enhanced emission intensity observed in dinuclear Sm-complexes, compared to their mononuclear counterparts, indicates a synergistic effect of the two metal ions on the overall emission properties, rather than a mere additive effect that would be expected from two independent mononuclear units. The photoluminescent properties of synthesized complexes were examined and discussed, suggesting potential applications in display devices. The Correlated Color Temperature (CCT) of these complexes falls within a range suitable for warm light sources and the highest branching ratio observed for 4G5/2 → 6H9/2 (for Sm3+ ion) and 4F9/2 → 6H13/2 (for Dy3+ ion) transitions suggests potential application in laser amplification. The alignment between band gap measurements obtained from UV and CV analyses highlight the possibility of employing these complexes in semiconductor technologies.

Complexes of a piperazine based macrocycle as Cu-Zn SOD biomimetic: approach by constants determination

Obtaining new compounds capable of catalyzing the dismutation reaction of the superoxide anion carried out by the enzyme Cu,Zn-SOD has become a topic of great interest. In the present work, the study of a ligand with a piperazine fragment and its Cu(II) and Zn(II) complexes is introduced. The protonation constants of the ligand, the stability constants of the complex species un with equivalent of Cu(II) and Zn(II), forming both mononuclear and heterobinuclear species, in the presence and absence of histidine as secondary ligand were determined. For all cases, species distribution diagrams were obtained, from which the spectra in the visible region of the species of greatest interest were obtained. As an approach to the Cu,Zn-SOD system, the formation of quaternary species formed between these ions, the main ligand and histidine as a secondary ligand, was verified, which could be used as mimetics of said enzyme. Some theoretical studies were carried out to support this study.

Co-targeting CDK 4/6 and C-MYC/STAT3/CCND1 axis and inhibition of tumorigenesis and epithelial-mesenchymal-transition in triple negative breast cancer by Pt(II) complexes bearing NH3 as trans-co-ligand

In search of potential anticancer agents, we synthesized SNO-donor salicylaldimine main ligand-based Pt(II) complexes bearing NH3 as co-ligand at trans-position (C1-C6). These complexes showed similarity in structure with transplatin as the two N donor atoms of the main ligand and NH3 co-ligand were coordinated to Pt in trans position to each other. Each complex with different substituents on the main ligand was characterized thoroughly by detailed spectroscopic and spectrophotometric methods. Four of these complexes were studied in solid state by single crystal X-ray analysis. The stability of reference complex C1 was measured in solution state in DMSO‑d6 or its mixture with D2O using 1H NMR methods. These complexes were further investigated for their anticancer activity in triple-negative-breast (TNBC) cells including MDA-MB-231, MDA-MB-468 and MDA-MB-436 cells. All these complexes showed satisfactory cytotoxic effect as revealed by the MTT results. Importantly, the highly active complex C4 anticancer effect was compared to the standard chemotherapeutic agents including cisplatin, oxaliplatin and 5-fluorouracil (5-FU). Functionally, C4 suppressed invasion, spheroids formation ability and clonogenic potential of cancer cells. C4 showed synergistic anticancer effect when used in combination with palbociclib, JQ1 and paclitaxel in TNBC cells. Mechanistically, C4 inhibited cyclin-dependent kinase (CDK)4/6 pathway and targeted the expressions of MYC/STAT3/CCND1/CNNE1 axis. Furthermore, C4 suppressed the EMT signaling pathway that suggested a role of C4 in the inhibition of TNBC metastasis. Our findings may pave further in detailed mechanistic study on these complexes as potential chemotherapeutic agents in different types of human cancers.

Chloride Gradient Is Involved in Ammonium Influx in Human Erythrocytes.

The ammonia/ammonium (NH3/NH4+, AM) concentration in human erythrocytes (RBCs) is significantly higher than in plasma. Two main possible mechanisms for AM transport, including simple and facilitated diffusion, are described; however, the driving force for AM transport is not yet fully characterized. Since the erythroid ammonium channel RhAG forms a structural unit with anion exchanger 1 (eAE1) within the ankyrin core complex, we hypothesized the involvement of eAE1 in AM transport. To evaluate the functional interaction between eAE1 and RhAG, we used a unique feature of RBCs to swell and lyse in isotonic NH4+ buffer. The kinetics of cell swelling and lysis were analyzed by flow cytometry and an original laser diffraction method, adapted for accurate volume sensing. The eAE1 role was revealed according to (i) the changes in cell swelling and lysis kinetics, and (ii) changes in intracellular pH, triggered by eAE1 inhibition or the modulation of eAE1 main ligand concentrations (Cl- and HCO3-). Additionally, the AM import kinetics was analyzed enzymatically and colorimetrically. In NH4+ buffer, RBCs concentration-dependently swelled and lysed when [NH4+] exceeded 100 mM. Cell swelling and hemolysis were tightly regulated by chloride concentration. The complete substitution of chloride with glutamate prevented NH4+-induced cell swelling and hemolysis, and the restoration of [Cl-] dose-dependently amplified the rates of RBC swelling and lysis and the percentage of hemolyzed cells. Similarly, eAE1 inhibition impeded cell swelling and completely prevented hemolysis. Accordingly, eAE1 inhibition, or a lack of chloride anions in the buffer, significantly decreased NH4+ import. Our data indicate that the eAE1-mediated chloride gradient is required for AM transport. Taken together, our data reveal a new player in AM transport in RBCs.

Synthesis and Performance of Deep-Red Phosphorescent Iridium Complexes with Pyrone as an Auxiliary Ligand.

Two bis-cyclometalated heteroleptic iridium complexes incorporating 1-phenylisoquinoline (piq) as the main cyclometalating ligand and 3-hydroxy-2-methyl-4-pyrone (ma) or 2-ethyl-3-hydroxy-4H-pyran-4-one (ema) as the auxiliary ligand, namely Ir(piq)2(ma) (Ir-1) and Ir(piq)2(ema) (Ir-2), were developed and applied as deep-red phosphors in organic light-emitting diodes (OLEDs). The two auxiliary ligands had similar influences on the photophysical, electrochemical, and electroluminescent properties of the iridium complexes. Ir(piq)2(ma) (Ir-1) showed better luminescence performance in a simple phosphorescent OLED compared to the traditional red iridium complex Ir(piq)2(acac) and exhibited a current efficiency of 9.39 cd A-1 (EQE of 12.09%). In contrast, Ir(piq)2(ema) exhibited an efficiency of 8.6 cd A-1 (EQE of 10.19%).

Rational design of red iridophosphors based on 1-(6-methoxynaphthalene-2-yl)isoquinoline ligand for solution‐processed OLEDs

Phosphorescent metal complexes find widespread application in organic light-emitting diodes (OLEDs), with iridium(III) complexes being particularly favored for their superior performance. Owing to the flexible modifications of both main and auxiliary ligands, the photophysical properties of iridium(III) complexes can be finely tuned. In this study, two red neutral iridium(III) complexes, designated as Ir1 and Ir2, are successfully synthesized and characterized. Various auxiliary ligands including acetylacetone and 2-picolinic acid are employed in combination with 1-(6-methoxynaphthalene-2-yl)isoquinoline as the cyclometalating ligand. Both complexes exhibit red emission, with Ir1 emitting at 631 nm and Ir2 at 615 nm. Furthermore, they demonstrated good solubility in common organic solvents, facilitating device fabrication via solution methods. Electroluminescent (EL) devices based on complexes Ir1 and Ir2 are further prepared using spin-coating method, achieving maximum external quantum efficiencies (EQEs) of 3.30 % and 4.52 %, respectively, and both devices exhibited bright red EL with CIE coordinates of (0.68, 0.32) and (0.66, 0.34), which were very close to the standard red coordinates of (0.67, 0.33).

Navigating the 18-n+m Isomers of PdSn2: Chemical Pressure Relief through Isolobal Bonds and Main Group Clustering.

The 18-n electron-counting rule provides structural guidelines for electronically feasible transition metal (T)-main group (E) phases, contributing toward the goal of material design. However, the availability of numerous potential structure types at any electron count creates a challenge for the prediction of the preferred structures of specific compounds, as is illustrated by the concept of 18-n+m isomerism. In this Article, we explore the driving forces stabilizing one 18-n+m isomer over another with an analysis of the structure of PdSn2, a layered intergrowth of the fluorite and CuAl2 structure types. The DFT-reversed approximation Molecular Orbital (DFT-raMO) method reveals that PdSn2 and its hypothetical parent structures all adhere to bonding schemes approximating the electronic configurations expected from the 18-n rule, with various degrees of isolobal Pd-Pd bonding and Sn clustering. However, partial electron transfer between the Pd 5p orbitals to the Sn 5s orbitals contributes to the absence of convincing electronic pseudogaps near their Fermi energies. As such, there is no clear electronically driven preference among the structure types. This situation allows for atomic packing effects to prevail: DFT-Chemical Pressure (DFT-CP) analysis illustrates that in the fluorite-type parent structure, positive Pd-Sn CPs lead to overcompression of the Pd atoms and a stretching of the relatively open Sn sublattice. In contrast, in the CuAl2-type parent structure, Sn atoms cluster into tetrahedra, opening space for an expanded Pd environment and the formation of Pd-Pd interactions. However, the tetrahedral packing of the Sn atoms here leads to frustration between negative and positive Sn-Sn CPs. Through the development of the angular CP correlation function (CPcor+) as a tool to quantify frustration among interatomic interactions, we demonstrate how the observed PdSn2 structure balances these effects by tuning the degree of Sn-Sn clustering and expansion of the Pd environment. These observations point to generalizations for most 18-n+m isomers, where increased main group ligand clustering (+m) and isolobal bonds (+n) can accommodate compositions with different T and E atomic sizes.

Photocytoxicity in vitro studies of ruthenium (II) complexes inducing cell death through targeting DNA

Photodynamic therapy (PDT) has been proven to be an important and effective therapy method with good spatial and temporal accuracy in clinical cancer treatment. Among many PDT candidates, Ru(II)-based compounds have received more attention due to their excellent photochemical and photophysical properties, high singlet oxygen (1O2) photogeneration, and DNA affinities. In this study, three ruthenium(II) complexes (RC1, RC2, RC3) have been designed by varying the aromatic plane area of the main ligand to adjust their 1O2 photogeneration, DNA affinities, DNA photodamage, and photocytoxicity. All complexes display no cytotoxicity in the dark against Hela, A549, HepG2, and BEL-7402 cells. RC1 displays no photocytotoxicity against all tumor cells. RC2 and RC3 showed high photocytotoxicity against BEL-7402 cells. The cellular uptake, cell migration, colonies assay, apoptosis analysis, and cell cycle analysis of RC2 and RC3 confirmed that the ruthenium(II) complexes might effectively enter the cancer cells, and lead to BEL-7402 cells apoptosis through DNA damage pathway. DNA photocleavage, DNA binding, and 1O2 measurement experiments demonstrated the DNA damage caused by RC2 and RC3 under light, compared to RC1, might be due to their high DNA affinities, large 1O2 quantum yields, and large lipophilicity by varying the aromatic plane area of the main ligand. Time dependent density functional theory (TDDFT) calculated results further show that two complexes exhibit the photocytotoxicity possibly via type II photoreaction mechanism because of the larger ΔS-T than O2 and strong SOC between Sn and Tm. Hence, rational design of ruthenium(II) complexes by increasing DNA affinities, 1O2 quantum yields and lipophilicity can be regarded as an effective approach for enhanced photodynamic therapy (PDT).