N-donor Co-ligands Research Articles

Two Mixed-Ligand Co(II) Complexes as Luminescent Materials and Loaded with Temozolomide-gel Particles in Nursing Against Glioma.

By employing a mixed-ligand strategy, we synthesized two new coordination polymers (CPs) featuring Co(II): {Co(H2L)(bib)]·2H2O}n (1) and {Co(L)(bib)2]·2H2O}n (2), where H4L represents 5-(3,5-dicarboxybenzyloxy) isophthalic acid, and bib denotes 1,4-bis(1-imidazolyl)benzene. These CPs were obtained through the reaction of H4L, a flexible carboxylic acid ligand, with Co(NO3)2·6H2O in various solvent mixtures, along with the N-donor co-ligand bib. Complexes 1 and 2 are formed through distinct coordination modes, resulting in their distinct structural features and excellent fluorescent properties. Based on ligand-centered fluorescence emission and the blue shift (CP 1) along with red shift (CP 2) characteristics, both complexes show promise for applications in fields such as blue fluorescence sensing materials and luminescent materials. After successfully synthesizing two CPs, CP 1 was chosen as the carrier for loading temozolomide (TMZ). Subsequently, leveraging the unique advantages of hydrogels, we developed a novel metal gel formulation loaded with TMZ. The inhibitory effect of this formulation on the growth of glioblastoma was evaluated. Our results demonstrate a significant suppression of glioblastoma cell proliferation by this system, providing an effective avenue for glioblastoma treatment.

Synthesis and Fluorescent Characteristics Study of Two Novel Co(II) Complexes.

In this work, two novel mixed-ligand CPs that has a compositions of [Co2(µ-Hdppa)2(phen)2(H2O)2] (1) and {[Co(µ-Hdppa)(µ-4,4'-bipy)(H2O)]·H2O}n (2) is achieved through reaction of cobalt salts with the 5-(3,4-Dicarboxylphenyl)picolinic acid (H3dppa) with various N-donor co-ligands (1,10-phenanthroline (phen) for 1 and 4,4'-bipyridine (4,4'-bipy) for 2). The structures and characteristics of these two complexes were fully examined via IR, TGA, and SXRD. Furthermore, their superior blue fluorescence properties compared to the original ligands were confirmed through fluorescence spectroscopy. These two complexes prepared in this study have enriched the choices for blue fluorescent materials.

Influence of ligand substitution and the solvent effect on the structures and magnetic properties of dinuclear Dy2 supramolecular architectures constructed with the bis-β-diketonate-Dy2 building block as a metalloligand.

Based on the bis-β-diketonate-Dy2 metalloligand [Dy2(pbth)4]·2Et3N (1, pbth = (3z,3'z)-4,4'-(1,3-phenylene)bis(1,1,1-trifluoro-4-hydroxybut-3-en-2-one)), six dinuclear complexes with eight-coordinated geometries were synthesized solvothermally through different capping N-donor coligands or solvent systems. These complexes are namely [Dy2(pbth)3(Phen)2]·2C2H5OH (2), [Dy2(pbth)3(BPhen)2]·2C2H5OH (3), [Dy2(pbth)3(Dppz)2]·2C2H5OH (4), [Dy2(pbth)3(Dppz)2]·2CH3OH (4a), [Dy2(pbth)3(4-Dmbp)2]·CH3OH·C2H5OH (5) and [Dy2(pbth)3(5-Dmbp)2]·CH3OH (6) (Phen = 1,10-phenanthroline, BPhen = 4,7-diphenyl-1,10-phenanthroline, dppz = dipyrido [3,2-a:2',3'-c] phenazine, 4-Dmbp = 4,4'-dimethyl-2,2'-bipyridyl, 5-Dmbp = 5,5'-dimethyl-2,2'-bipyridyl), respectively. In the synthetic processes of 2-6, one of four bis-β-diketonate ligands in the metalloligand is replaced by two capping N-donor coligands. The coordination geometries, metal distances and M-L-M torsion angles of the synthesized complexes are perceptibly fine-tuned by the modification of the capping N-donor coligands or the latticed solvent molecules. Systematic magnetic investigations indicate the different magnetic relaxation dynamics of 1-6. Complex 1 displays no characteristics of single-molecule magnets (SMMs), while complexes 2-6 exhibit SMM behaviours in the absence of a static magnetic field. Complexes 2 and 3 possess effective energy barriers (Ueff) of 110.18 (2) K and 133.21 (4) K, respectively. Theoretical analysis based on ab initio calculation provides some interpretations of experimental observation.

Aza-donor ligands—A key to synthesizing mononuclear to coordination polymers of cadmium phosphinates

Four cadmium phosphinate complexes were synthesized based on Bis-[α-hydroxy(p-methylphenyl)methyl]phosphinic acid (L) ligand. These complexes [Cd(L)2(H2O)2] (1), [Cd(L)2(py)3].py (2), [Cd(L)2(4,4’-bpy)4]n(3), [Cd(L)4(4,4’-azo-bpy)(H2O)]n(4), were well characterized by single crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction, elemental analysis and TGA. 1 and 2 are zero-dimensional(0D) structures while 3 and 4 are two dimensional net-like(2D), one dimensional chain-like(1D) structures, respectively. N-donor co-ligands(py, 4,4’-bpy, 4,4’-azo-bpy) contribute to the formation of these architectures.

Synthesis, crystal structures and properties of six new mixed ligand cobalt(II) 4-nitrobenzoates

The synthesis, spectral characteristics, thermal properties and single crystal structures of [Co(N-meim)2(4-nba)2] (N-meim = N-methylimidazole; 4-nba = 4-nitrobenzoate) (1), [Co(2-meim)2(4-nba)2] (2-meim = 2-methylimidazole) (2), [Co(pyr)3(4-nba)2] (pyr = pyrazole) (3), [Co(H2O)2(form)2(4-nba)2]·form (form = formamide) (4), [Co(H2O) (aceta)2(4-nba)2] (aceta = acetamide) (5) and [Co(H2O)3(N-mepyr)(4-nba)](4-nba) (N-mepyr = N-methylpyrazole) (6) are reported. The central Co(II) exhibits tetrahedral geometry in 1 and 2, trigonal bipyramidal geometry in 3 and octahedral geometry in 4–6. In the anhydrous compounds 1–3 as well as the diaqua compound 4, the monoaqua compound 5 and the triaqua compound 6, the neutral N-donor co-ligands or the O-donor amides function as terminal ligands. The aromatic 4-nba ligand exhibits monodentate binding mode in 1–4 and monodentate and bidentate binding in 5, while 6 contains an uncoordinated 4-nba in addition to a bidentate 4-nba ligand. A single C-H···O interaction links molecules of 1 into an infinite chain while the N-H···O bonds in 2 result in a two-dimensional network. Compounds 4 and 5 exhibit three varieties of H-bonding. Thermal decomposition of 1–6 results in the formation of a spinel oxide. A comparative study of thirty-one structurally characterized cobalt-4-nitrobenzoates is described.

Two new Zn(II) and Cd(II)-based metal-organic frameworks constructed from pamoic acid and N-donor co-ligands

Two new Zn(II) and Cd(II)-based metal-organic compounds, namely [Zn(pam)(bpe)]n (1) and [Cd(pam)(bib)(H2O)2]n·n(DMF) (2) (H2pam = pamoic acid, bpe = 1,2-bis(4-pyridyl)ethylene, bib = 1,4-bis(imidazole-1-yl)butane), have been synthesized by the self-assembly of metal ions, pamoic acid, as well as N-donor co-ligands under hydrothermal or solvothermal conditions. X-ray diffraction analyses revealed that compound 1 is a 4-fold interpenetrated 3D framework, representing a 4-connected dia topology, and compound 2 shows a 2D layer structure with 4-connected sql topology. The luminescent properties of these two compounds were also investigated.

RETRACTED: Cervical cancer treatment of Co(II) coordination polymer through miR-9-5p-regulated BRCA1-OCT1-GADD45 pathways

Fresh Co(II) concluding coordination polymer based on {[Co(μ-ppda)(μ-pbmeix)]∙0.5pbmeix·H 2 O} n ( 1 ) was formed smoothly through the reaction of Co(II) salt with p -phenylenediacetic acid (H 2 ppda) under the conditions of N-donor co-ligand semirigid 1,4-bis(2-methylimidazol-1-ylmethyl)benzene (pbmeix) for cervical cancer therapy. In our biological research, we explored the pathogenesis of cervical cancer and provided new targets for cervical cancer treatment. In patients with cervical cancer and the cervical cancer rat model, the expression of Breast Cancer Susceptibility Protein-1 (BRCA1) was aberrantly upregulated. This phenomenon may play a role in the occurrence and development of cervical cancer. Then, bioinformatics prediction was conducted, and miR-9-5p was speculated as the up-regulator of BRCA1 in cervical cancer cells. The influence of miR-9-5p on the vascular endothelial growth factor and pigment epithelium-derived factor contents of cervical cancer lesions was determined via enzyme‐linked immunosorbent (ELISA) assay. Then, the proliferation of cervical cancer cells was determined via CCK-8 assay after miR-9-5p transfection. Finally, we proved that complex 1 is an excellent candidate for cervical cancer therapy through miR-9-5p-regulated BRCA1-OCT1-GADD45 pathways.

Effect of N-donor ancillary ligand on zinc/cadmium-organic arsonates: Structural analysis and photoluminescence

The design and construction of metal organic frameworks (MOFs) or coordination polymers (CPs) with tunable structures is of great interest in recent years, owing to their intriguing structural diversity and potential applications. The mixed-ligand approach is widely used as an effective synthesis method to fabricate CPs. By precise regulation of the structure of N-donor co-ligands, in this work, a series of zinc/cadmium-organic arsonates are successfully synthesized, namely, [Zn2(OH)(L-As)(4,4′-Bipy)⋅H2O]n (1), [Zn3(L-As)2(2,2′-Bipy)(H2O)2⋅2H2O]n (2), [Cd(HL-As)(4,4′-Bipy)0.5]n (3), [Cd(HL-As)(2,2′-Bipy)(H2O)⋅H2O]n (4) (H3L-As ​= ​2-(carboxymethylamino)phenylarsonic acid; 4,4′-Bipy ​= ​4,4′-bipyridine; 2,2′-Bipy ​= ​2,2′-bipyridine). We demonstrate that N-donor co-ligands significantly affect the coordination environment of metal centers and the structure of these compounds. Compound 1 is a three-dimension (3D) hydrogen-bond network via C–H···π interactions between the aromatic rings of L-As ligand, whereas 3 exhibits a 3D framework with 6-connected pcu topological network. By contrast, 2 and 4 are two-dimension (2D) layered structures by adopting chelated 2,2′-Bipy Co-ligand. All compounds display a luminescence from ligand-to-metal charge transfer (LMCT) which depends on the coordination environment of metal centers. The results show that N-donor co-ligands can effectively regulate the structures and luminescent properties of the formed CPs.

Application value of a new Cu(II)-coordination polymer in stroke rehabilitation treatment and nursing by reducing oxidative stress in nerve cells

In this current work, through employing the mixed-ligand generation approach, a fresh coordination polymer on the basis of Cu(II), that is, {(H2bpe)[Cu(HL)2(bpe)(H2O)2]·(H2O)4}n (1) has been created with a reaction between 4-(2′,3′-dicarboxylphenoxy) benzoic acid (H3L), a semi-rigid tricarboxylate acid and Cu(NO3)2·3H2O, in the existence of the N-donor co-ligand 1,2-bis(4-pyridyl) ethylene (bpe) with HBF4 as the pH modulator. Its application value in stroke rehabilitation treatment and nursing was explored and the associated mechanism was analyzed simultaneously. Through the molecular docking simulation, those experimentally observed biological activities can be attributed to the hydrogen bonding interactions between the carboxyl groups on the Cu coordination polymer and the active sites on the receptor protein.

Two Mixed-Ligand Cu(II) Polymers: Treatment Activity on Acute Cerebral Infarction Combined with Alteplase

With the reaction between Cu(NO3)2·3H2O and 4-(2 ′ ,3 ′ -dicarboxylphenoxy) benzoic acid (H3L), a semirigid trichromatic acid ligand, in the presence of N-donor co-ligand 1,2-bis(4-pyridyl) ethylene (bpe), two novel mixed-ligand coordination polymers (CPs), i.e., [Cu(H2L)2(bpe)(H2O)2]bpe·(H2O)4 (1) and [Cu3(L)2(bpe)3(H2O)4]·(H2O)6 (2), have been created under different solvent systems. Furthermore, the biological activity of compounds was evaluated, and the related mechanism was explored as well. Firstly, the enzyme-linked immunosorbent assay (ELISA) was conducted to measure the content of coagulation factors in the serum after compound treatment. In addition to this, the real-time reverse transcription-polymerase chain reaction (RT-PCR) assay was conducted, and the inflammatory response in the brain was also determined.

Three coordination polymers as a multi-responsive luminescent probe for the detection of Fe3+, Cr2O72− and antibiotic in aqueous media

Three coordination polymers (CPs), namely {[Co(L)(dpa)]·H2O}n (1), {[Zn(L)2(dpb)]}n (2) and {[Zn(L)(dpe)]}n (3), have been assembled through a dual-ligand strategy of a semi-rigid dicarboxylic acid (H2L = 1,4-bis(4-phenoxy)benzenedicarboxylic acid) with the help of different N-donor co-ligands (dpa = di(pyridin-4-yl)amine, dpb = 1,4-di(pyridin-4-yl)benzene), dpe = trans-1,2-di(4-pyridyl)ethylene). Single crystal X-ray diffraction analyses reveals that compound 1 is a 4-fold interpenetrating 2D sql network and compound 2 is a 2-fold interpenetrating 2D sql network, although the final structures are different because of various inter-layer stacking modes. Compound 3 is a 8-fold interpenetrating 3D dia framework containing an octahedral cage. A photoluminescence investigation shows that compounds 2 and 3 exhibit strong fluorescence originating from the intra-ligand charge transfer transitions. Benefiting from its chemical stability and luminescent properties, compound 2 possesses multi-functional fluorescent responses toward the Fe3+ ion, the Cr2O72− ion and the NZF antibiotic in aqueous medium. The KSV values of compound 2 are 4.68 × 104 M−1 for the Fe3+ ion, 7.23 × 104 M−1 for the Cr2O72− anion, and 1.03 × 104 M−1 for the NZF antibiotic. Additionally, the possible mechanism for the luminescence quenching has been investigated.

RETRACTED: Inhibition of two Cu(II) and Mn(II) coordination polymers on the surgical site infections by inhibiting the bacterial biofilm formation

Within this work, two novel Cu(II) and Mn(II)-based coordination polymers (CPs) along with chemical compositions of {[Cu 2 ( L 1 )(1,4-NDC) 2 ]·3H 2 O} n ( 1 , 1,4-H 2 NDC = Naphthalene-1,4-dicarboxylic acid, L 1 ​= ​di(1 H -imidazole-1-yl)methane) and [Mn 3 ( L 2 ) 2 (H 2 O) 2 (1,4-NDC) 2 ] n ( 2 , L 2 ​= ​1,4-di(1 H -imidazole-1-yl)benzene) have been completed in success via related metal salts reaction with 1,4-H 2 NDC ligand in existence of various N-donor co-ligands. We discovered its application values on the surgical site infections (SSI) along with corresponding mechanism in the interim. We evaluated inflammatory cytokines released into the urine through ELISA detection kit after compound treatment. Then, we discovered the inhibitory effect of compound on the bacterial biofilm formation via real time RT-PCR. • Two Cu(II) and Mn(II)-based coordination polymers were prepared. • Their structures have been studied. • Their bioactivity on surgical site infections were evaluated.

RETRACTED: Treatment application values of Cu(II)-coordination polymer on infection after ureteroscopic lithotripsy

In the current study, via using the mixed-ligand synthesis method, a novel Cu(II)-based coordination polymer with the chemical formula of [Cu(L)(D-CAM)(H 2 O)] n ( 1 ) has been completed in success via Cu(NO 3 ) 2 ·3H 2 O reacting with the (1 ​ R ,3 ​ S )-1,2,2-trimethylcyclopentane-1,3-dicarboxylic acid (D-H 2 CAM) in existence of N-donor co-ligand 3,6-bis(benzimidazol-1-yl)pyridazine. We discovered this treatment application value regarding of infection after ureteroscopic lithotripsy along with corresponding mechanism in the interim. At first, enzyme linked immunosorbent assay (ELISA) was conducted and inflammatory cytokines content like interleukin-1 β (IL-1β) and tumor necrosis factor (TNF-α) released into the plasma after the compound treatment was measured. Besides, we adopted real time reverse transcription-polymerase chain reaction (RT-PCR) determination and degrees of bacterial growth-linked gene expression were determined as well. • A novel Cu(II)-based coordination polymer was prepared. • Its crystal structure was also obtained. • Its bioactivity on infection was studied.

Structural diversity in four Zn(II)/Cd(II) coordination polymers tuned by flexible pentacarboxylate and N-donor coligands: Photocatalysts for enhanced degradation of dyes

Coordination polymers (CPs) are peculiar class of multidimensional materials which can be employed as photocatalytic materials to decompose lethal aromatic dyes present in waste-water discharge. Herein, four new Zn(II)/Cd(II) coordination polymers (CPs) namely [Cd2(H2O)(H3L)2(2,2′-bipy)2]·H2O (1), [Zn2(HL)(H2O)2(2,2′-bipy)2]·H2O (2), [Cd2(HL)(bmb)0.5(H2O)]·2H2O (3) and [Zn4(L)2(bpz)4·H2bpz]·4H2O (4) (H5L = 3,5-bis(3,4-dicarboxylphenoxy)benzoic acid, 2,2′-bipy = 2,2′-bipyridine, bmb = 1,4-bis(2-methylimidazol-1-yl)butane, bpz = 3,3′,5,5′-tetramethyl-4,4′-bipyrazole), have been synthesized solvothermally and characterized. The single crystal X-ray diffraction reveals that CPs 1 and 2 exhibit 2D supramolecular framework built by the hydrogen bond interactions between adjacent chains. The CP 3 features a 2D double layer while 4 display 3D 3,3,4,4-connected topology with point symbol {4.6.84}{4.6.8}{62.84}{62.8}. All these newly synthesized materials exhibit photocatalytic properties and the results demonstrated that they exhibit efficient photocatalytic performances to selectively degrade methylene blue (MB) among the dyes viz. methylene orange (MO), acid orange (AO), congo red (CR) and acid chrome blue (ACB) under UV irradiation. A mechanistic investigation toward better understanding of the photocatalytic degradation of MB has been carried out using LC-MS studies. Also computational investigation by performing band gap calculations have been accomplished to address the probable mechanistic pathway which further have been assisted with Hirshfeld surface analysis.

RETRACTED ARTICLE: Two Cu(II)-coordination polymers: structural diversity and anti-ovarian cancer evaluation

We, the Editors and Publisher of the journal Inorganic and Nano-Metal Chemistry, have retracted the following article: Ting-Ting Yao, Feng-Feng Ning, Tian-Gang Li, Mei-Li Wu & Xiao-Xia Wang (2021): Two Cu(II)-coordination polymers: structural diversity and anti-ovarian cancer evaluation, Inorganic and Nano-Metal Chemistry, DOI: 10.1080/24701556.2021.1952253 Since publication, concerns have been raised about the integrity of the data in the article. When approached for an explanation, the authors have been unable to address the concerns raised and have not been able to provide sufficient supporting information. As verifying the validity of published work is core to the integrity of the scholarly record, we are therefore retracting the article. The corresponding author listed in this publication has been informed. The authors have agreed to the retraction. We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

RETRACTED: Two Co(II)-organic frameworks: Selective gas sorption and treatment activity on thecal cyst

• Two new metal-organic frameworks (MOFs) were prepared. • 2a might be made available for the exclusion of C 2 H 2 /CH 4 or CO 2 /CH 4 . • Compound 1 has more distinguished activity in contrast to compound 2. In this article, two new metal-organic frameworks (MOFs), namely, {[Co(HBTB)(pdp)]•H 2 O} ( 1 , pdp = 2-(4,6-di(pyridine-2-yl)pyridine-2-yl)pyridine)) and {[Co 6 (OH) 4 (BTB) 8/3 (H 2 O) 6 ]•4H 2 O•9DMF} n ( 2 ) have been produced by reaction of Co(NO 3 ) 2 •6H 2 O and the 1,3,5-benzenetribenzoic acid (H 3 BTB) with the presence of different N-donor co-ligands (pdp for 1 and 1H-Benzotriazole for 2 ). The pdp ligand in complex 1 blocks the coordination sites of the Co(II) ion, result in the establishment of a 1D chain-like structure of 1 . While the 1H-Benzotriazole did not participate in in the formation of the framework of 2 , but acts a template to shape a cluster-based framework, resulting in a highly porous framework which shows outstanding C 2 H 2 /CH 4 (1:1) and CO 2 /CH 4 (1:1) exclusions with the IAST selectivity at 23.6 and 11.3 at 298 K (100 kPa) after activation. In this biological experiment, CCK-8 was used to estimate the promoting effect of these compounds on the activity of tendon cells. Then, the relative expression of the important inflammatory gene p53 was detected after compounds 1 and 2 treatment. Besides, the influence of the p53 on the FAK signaling pathway was explored with luciferase assay. Finally, the activation of the FAK signaling pathway was determined with western blot. Compound 1 was more excellent than compounds 2 on the thecal cyst treatment.

Multifunctional sensing activities toward heavy metals of three luminescent complexes: Effect of N-donor coligands and sensing medium

The functional groups and flexibility of organic building blocks were crucial for regulating the structure and luminescence as well as detecting activity of MOFs. Three Complexes of a flexible carboxylate ligand with –CH2-O- groups, namely, [Cd3(L)2(DMF)4]n (1), {[Cd3(L)2(bpea)3(H2O)4]∙2H2O∙4DMF}n (2), and [Cd3(L)2(bpy)]n (3) (H3L = 3,5-bis[(3-carboxyphenyl)oxy]benzoic acid, bpea = bis(pyridyl)ethane, and bpy = 4,4′-bipyridine), were synthesized under solventhermal conditions. Both complexes 1 and 2 exhibit interesting 2-D trilayer structures with (3,6)- and (3,4,6)-connected topology, respectively. Complex 3 displays 3-D complicated framework, in which Cd2+ ions are connected by the carboxylate groups of L3− ligands into 3-D motifs and further linked by bpy ligands. The flexible carboxylate ligand adopts three different coordination modes with the aromatic rings forming diverse dihedral angles. Luminescence measurements reveal that both the frameworks and the solvents play an important role on the sensing activities. Three complexes can selectively and sensitively detect Fe3+ and Cr2O72− in DMF through luminescence quenching (turn-off) with the latter two showing high water stability and sensing activities toward Fe3+ and Cr(VI) (Cr2O72− and CrO42−). The detection limits are in the range of 0.21–2.05 μM, comparable or superior to those of previous luminescence sensors. Specially, complex 3 could also detect Pb2+ in H2O with detection limit of 1.43 μM (0.30 ppm). The building units, the structures, the sensing media all have an effect on the sensing activities. Possible quenching mechanisms for detection of these ions were carefully investigated and proposed based on luminescence inner filter effect (IFE) and weak interactions between the target ions and frameworks. Moreover, the recoveries of 96.7–103.4% for the detection of above ions in tap water samples are achieved, suggesting practical application.

Synthesis, characterization of Uranyl(VI), Th(IV), Zr(IV) mixed-ligand complexes with S-methyl-2-(4-methoxybenzylidine)dithiocarbazate and N-donor co-ligand, and their evaluation as antimicrobial agent

Schiff base, S-methyl-2-(4-methoxybenzylidine) dithiocarbazate as a primary ligand (HL1), quinoline (L2) as a co-ligand, and hydrated metal salts have been reacted in ethanol in 1:2:1 M ratio to produce mixed-ligand complexes of the type, [M(L1)(L2)].NO3 [M = Uranyl(VI), Th(VI), Zr(IV)], The isolated products have been structurally investigated by elemental analyses, 1H NMR, IR and UV–Vis studies. The electronic studies shows octahedral geometry for all the studied complexes, whereas the molar conductance data suggest an ionic nature. Density functional computation (DFT) studies are also carried out in order to determine the bonding inside the structure of the complexes. The studied mixed-ligand complexes showed moderate antibacterial activity when evaluated against four pathogenic bacteria: Shigella dysenteriae, Bacillus subtilis, Agrobacterium tumefaciens, and Escherichia coli. In addition, molecular docking analysis for all the complexes, using the CLC Drug Discovery Workbench software, showed that they virtually docked on S. dysenteriae, B. subtilis, A. tumefaciens, and E. coli.

Syntheses, Structures and Magnetic Properties of Cobalt(II) Coordination Polymers Based on Semi-Rigid Polycarboxylic Acid Ligand

Herein, two new Co(II) CPs, {[Co(H3L)(bpa)]·H2O}n (1) and {[Co2(H3L)2(phen)2(H2O)2]·3H2O}n (2) were hydrothermally obtained based on O-donor semi-rigid polycarboxylic acid ligand H5L (5,5’-((5-carboxy-1,3-phenylene)bis(oxy))diisophthalic acid) and N-donor coligands, such as bpa (1,2-bis(4-pyridyl)ethane), phen (1,10-phenanthroline hydrate). Both of them were studied by single crystal X-ray diffraction analysis, thermogravimetric analysis, infrared spectra, powder X-ray diffraction and variable-temperature magnetic susceptibilities. CP 1 features a one-dimensional chain, further stacked to a two-dimensional layer and three-dimensional structure through π···π stacking interactions and hydrogen bonds. CP 2 displays two-dimensional layers, which further extended into three-dimensional frameworks through C−H···π interactions and hydrogen bonds. In addition, variable-temperature magnetic susceptibility data were investigated, indicating that the CPs 1 and 2 exhibited antiferromagnetic interactions.

Regulating the magnetic dynamics of mononuclear β-diketone Dy(iii) single-molecule magnets through the substitution effect on capping N-donor coligands.

A series of five mononuclear β-diketonate-Dy(iii) complexes, with formulas Dy(ntfa)3(Br-bpy) (1), Dy(ntfa)3(Br2-bpy) (2), Dy(ntfa)3(5,5-(CH3)2-bpy) (3), Dy(ntfa)3(4,4-((CH3)3)2-bpy) (4) and Dy(ntfa)3(4,4-(CH3)2-bpy) (5) (ntfa = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione, Br-bpy = 5-bromo-2,2'-bipyridine, Br2-bpy = 4,4'-dibromo-2,2'-bipyridine, 5,5-(CH3)2-bpy = 5,5'-di-methyl-2,2'-bipyridine, 4,4-((CH3)3)2-bpy = 4,4'-di-tert-butyl-2,2'-bipyridine, and 4,4-(CH3)2-bpy = 4,4'-di-methyl-2,2'-bipyridine), have been prepared by altering the capping N-donor coligands. Dy(iii) ions in all complexes possess N2O6 octa-coordinated environments, displaying a distorted square antiprismatic D4d symmetry in complexes 1-4, as well as a triangular dodecahedron D2d symmetry in 5. Magnetic investigations evidence the SIM behavior in the five complexes with the energy barriers (Ueff) of 104.19 K (1), 122.93 K (2), 84.20 K (3), 64.16 K (4) and 80.23 K (5) under zero applied dc field. The potential QTM effects in the title complexes are successfully suppressed in the presence of the extra applied fields. The crystal field parameters and orientations of the magnetic easy axes were obtained from the simulation of the magnetic data and the electrostatic model calculation. The distinct electronic effects originating from the subtle changes of the substituents on the capping N-donor coligands induce varying coordination microenvironments and geometries on the Dy(iii) sites, further drastically impacting the overall magnetic properties of the title complexes. The disparities of the uniaxial anisotropy and the magnetic dynamics for 1-5 have been elucidated by ab initio calculations as well.