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Herein, the synthesis, structural characterization, magnetic properties and guest binding activities of four Fe3+ based double-stranded helicates namely; [Fe2(L)2](ClO4)(Cl)·4(CH3OH)·2(H2O) (1), [Fe2(L)2](BF4)2·2(H2O) (2), [Fe2(L)2](NO3)2·3(CH3OH)·2(H2O) (3), and [Fe2(L)2](Cl)2·2(CH3OH)·4(H2O) (4) are reported. Complexes 1–4 have been synthesized using the hydrazide-based ligand H2L (H2L = N′1,N′4-bis(2-hydroxybenzylidene)succinohydrazide) and the corresponding Fe2+ salts. Each of the independent cationic complexes [Fe2(L)2]2+ shows double-stranded helicates from the self-assembly of the ligand and metal ions in a 2 : 2 ratio, where the individual Fe3+ centre is lying on a C2-axis and the ligand strands wrap around it. In 1–4, ligand L adopts “pseudo-C” conformations and forms a double-stranded dinuclear helicate with a small cage in between them. Moreover, in 1–4, each of the independent cationic complexes [Fe2L2]2+ is inherently chiral and possesses P for right-hand and M for left-hand helicity and as a consequence is a racemic solid. Detailed magnetic studies of all the complexes reveal that the Fe3+ centres are magnetically isolated and isotropic in nature. Estimation of the Magnetocaloric Effect (MCE) from magnetization data unveils a moderate MCE at a temperature of 3 K with magnetic entropy changes (−ΔSm) of 22.9, 27.7, 24.1, 26.5 J kg−1 K−1 at a magnetic field of 7 T for complexes 1–4, respectively. Also, the variation of the −ΔSm values was justified by considering the parameter of magnetization per unit mass. Stability of all the complexes in solution phase was confirmed by ESI-mass spectrometric analysis and liquid phase FT-IR spectroscopy. Further, the interaction of the complexes 1–4 with Rhodamine B dye was examined by UV-vis and fluorescence spectroscopic study. The observed blue-shift in the fluorescence study and hyperchromicity and hypochromicity with the appearance of two isosbestic points in the UV-vis study ascertain the interactions of the dye with the complexes. A DNA binding study by absorption spectral titration suggests the weak external intercalation of complex 1 within the nucleotide of calf thymus DNA. Computational study supports the isotropic nature of the metal centres and the consequent high spin multiplicity, which assists the complexes to show significant magnetic entropy changes. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of two isoreticular metal-organic frameworks (MOFs), {[Cd(bdc)(4-bpmh)]}n·2 n(H2O) (1) and {[Cd(2-NH2bdc)(4-bpmh)]}n·2n(H2O) (2) [bdc=benzene dicarboxylic acid; 2-NH2bdc=2-amino benzene dicarboxylic acid; 4-bpmh=N,N-bis-pyridin-4-ylmethylene- hydrazine], are reported. Both compounds possess similar two-fold interpenetrated 3D frameworks bridged by dicarboxylates and a 4-bpmh linker. The 2D Cd-dicarboxylate layers are extended along the a-axis to form distorted square grids which are further pillared by 4-bpmh linkers to result in a 3D pillared-bilayer interpenetrated framework. Gas adsorption studies demonstrate that the amino-functionalized MOF 2 shows high selectivity for CO2 (8.4 wt% 273 K and 7.0 wt% 298 K) over CH4, and the uptake amounts are almost double that of non-functional MOF 1. Iodine (I2) adsorption studies reveal that amino-functionalized MOF 2 exhibits a faster I2 adsorption rate and controlled delivery of I2 over the non-functionalized homolog 1. [ABSTRACT FROM AUTHOR]

We present a robust two dimensional coordination polymer, [Ni2(L)2(N(CN)2)2]n (1) (LH = 2-((1-(pyridin-2-yl)ethylimino)methyl)-phenol; N(CN)2 - = dicyanamide ion) using a chiral Schiff base (LH), which shows diastereoselectivity in the structure via a chiral selfdiscrimination process, ferro- and antiferromagnetic interactions among the metal centers and unusual CO2 uptake behavior as a porous framewok. [ABSTRACT FROM AUTHOR]

Two unique lanthanide-based cages [Ln10( L)5(μ2-OH)6(H2O)22](Cl)4⋅7 H2O ([Gd10] and [Dy10]) have been synthesized by using a hydrazone-based ligand H4 L (H4 L=2,6-bis[(3-methoxysalicylidene)hydrazinecarbonyl]pyridine) and LnCl3⋅ x H2O. Structural characterization of [Gd10] reveals an aesthetically pleasing self-assembly of five L4− and ten Gd3+ ions forming a 2×[1×5] rectangular array. The ladder-shaped cage consists of three 'rungs' and two 'rails' that are occupied by five ligands. Six out of ten gadolinium centers act as rung locks. Further analysis revealed that three chloride ions are encapsulated inside each discrete [Gd10] molecule through hydrogen bonding and other noncovalent interactions. Both the complexes ([Gd10] and [Dy10]) were characterized by powder X-ray diffraction and thermogravimetric analysis, which shows that they are isostructural in nature. Magnetic investigations reveal that [Gd10] is a good candidate for magnetic refrigeration with a significant entropy change (−Δ Sm) of 37.4 J kg−1 K−1 for an applied field of 7 T and at 3 K. Whereas [Dy10] shows single-molecule-magnet-like behavior. [ABSTRACT FROM AUTHOR]

This article details our efforts to prepare free-standing macroscopic films by optimized coordinative crosslinking of poly(4-vinylpyridine) (P4VP) chains using transition metal ions. We encountered homogenous gels (at <1% w/v polymer concentration) en route to the fabrication of such films. The gels and films were obtained through coordinative crosslinking of P4VP chains by Ni(ii) ions while the use of other metal ions (viz. Co(ii), Cu(ii) or Zn(ii)) for this purpose resulted in either heterogeneous gels or gelatinous precipitates. Based on the gelation kinetics and the mechanical strength of the resulting films, the most optimum coordination ratio was observed to be 1 : 1 molar ratio of 4VP : Ni(ii) in the methanol–water mixed solvent system. Highly transparent, flexible, free-standing films of any dimension and shape could be fabricated through controlled evaporation of the solvent from the gels. The microscopic features of these films were quite similar to those of xerogels. Magnetic susceptibility measurements performed on the ground films showed ferromagnetic interactions between adjacent Ni(ii) centres in the temperature range of 75 to 10 K. These coordinatively crosslinked pliable films exhibited selective, although moderate, adsorption of environmentally relevant CO2 at room temperature. Through variation of the metal content in the films, we further demonstrated that the metal centres present in the film are intimately involved in the adsorption of CO2. We believe such coordinatively crosslinked polymer films can be a potential alternative to metal–organic frameworks (MOFs) in gas adsorption applications, with the added benefit of flexibility and macroscopic dimensions. [ABSTRACT FROM AUTHOR]

Tuning the bridging fashion of anilato ligand in dinuclear DyIII complexes, reveals a sizable effect on the slow relaxation of magnetization. Combined experimental and theoretical studies divulge that the geometry with high order axial symmetry (pseudo square antiprism) reduces the transverse crystal fields corresponding to QTM (quantum tunneling of magnetization) resulting in a significant increase in energy barrier (Ueff=518 cm-1) through the Orbach relaxation process whereas the geometry with lower symmetry (triangular dodecahedron, pseudo D2d) enhances the transverse crystal fields that accelerate the ground state QTM process. Notably, the value 518 cm-1 represents the highest energy barrier among anilato ligand based SMMs. [ABSTRACT FROM AUTHOR]

We report the synthesis, structures, and magnetic properties of twelve iron(Ill) phosphonate cages: [Fe[sub4](μ[sub3]-O)CI(PhCO[sub2])[sub3-](PhPO[sub3])[sub3](py)[sub5]] 1, [Fe4(μ[sub3]-O)([supt]BuCO[sub2])[sub4](C[sub10]Hi[sub7]PO[sub3])[sub3](py)[sub4]] 2 (C[sub10]H[sub17]PO[sub3]H[sub2] = carnphyIphosphonic acid), [Fe[sub7](μ[sub3]-O)[sub2](PhPO[sub3])[sub4](MeCO[sub2])[sub9](py)[sub6]) 3, [Fe[sub7](μ[sub3]-O)[sub2](PhPO[sub3])[sub4](PhCO[sub2])[sub9](py)[sub6]] 4, [Fe[sub7](μ[sub3]-O)[sub2]( BuPO[sub3])[sub4]([supt]BuCO[sub2])[sub8](py)[sub8]](NO[sub3]) 5, [Fe[sub7](μ[sub3]-O)[sub2](PhPO[sub3])[sub4](MeCO[sub2])[sub8](py)[sub8]] 6, [Fe[sub9](μ[sub3]-O)[sub2](μ[sub2]-OH)(PhPO[sub3])[sub6]([supt]BuCO[sub2])[sub10](MeCN)(H[sub2]O)[sub5]] 7, [Fe[sub9](μ[sub3]-O)[sub2](μ[sub2]-OH)(C[sub10]H[sub17]PO[sub3])[sub6](PhCO[sub2])[sub10](H[sub2]O)[sub6]] 8, [Fe[sub6](μ[sub3]-O)[sub2](O[sub2])( BuCO[sub2])[sub8](PhPO[sub3])[sub2](H[sub2]O)[sub2]] 9, [Fe[sub6](μ[sub3]-O)2(O[sub2])([supt]BuCO[sub2])[sub8](C[sub10]H[sub17-]PO[sub3])[sub2](H[sub2]O)[sub2]] 10, [Fe[sub6](μ[sub3]-O)[sub2](O[sub2])(BuCO[sub2])[sub8](BuPO[sub3])[sub2](py)[sub2]] 11, and [Fe[sub14](μ[sub3]-O)[sub4](O[sub2])[sub2](PhPO[sub3])[sub8]([supt]BuCO[sub2])[sub12](H[sub2]O)[sub12]](NO[sub3])[sub2] 12. The results have allowed us to compare the magneft exchange found with magneto-structural correlations found previously for iron-oxo cages. [ABSTRACT FROM AUTHOR]

Two structurally dissimilar 3d-4f cages having the formulae [(CoIII)3Gd4(μ3-OH)2(CO3) (O2CtBu)11(teaH)3]·5H2O (1) and [(CoIII)3Dy3(μ3-OH)4(O2CtBu)6(teaH)3]·(NO3)2·H2O (2) have been isolated under similar reaction conditions and stoichiometry of the reactants. The most important factor for structural diversity seems to be the incorporation of one μ3-carbonate anion in 1 and not in 2. Co atoms are in a +3 oxidation state in both complexes, as shown by the Bond Valence Sum (BVS) calculations and bond lengths, and as further supported by magnetic measurements. Co3Gd4 displays a significant magnetocaloric effect (−∆Sm = 25.67 J kg−1 K−1), and Co3Dy3 shows a single molecule magnet (SMM) behavior. [ABSTRACT FROM AUTHOR]

Three new copper(ll) complexes, [CuL1(NO2)]n (1), [CuL2(NO2)] (2), and [CuL3(NO2)] (3), with three similar tridentate Schiff base ligands [HL1 = 6-amino-3-methyl-1-phenyl-4-azahept-2-en-1-one, HL2 = 6-amino-3-methyl-1-phenyl- 4-azahex-2-en-1-one, and HL3 = 6-diethylamino-3-methyl-1-phenyl-4-azahex-2-en-1-one] have been synthesized and characterized structurally and magnetically. In all three complexes, the tridentate Schiff base ligand and one oxygen atom of the nitrite ion constitute the equatorial plane around Cu(ll), whereas the second oxygen atom of the nitrite ligand coordinates to one of the axial positions. In 1, this axially coordinated oxygen atom of the nitrite ligand also coordinates weakly to the other axial position of a Cu(ll) ion of another unit to form a one-dimensional chain with the μ-nitrito-1k2O, O:2kO bridging mode. Complexes 2 and 3 are discrete monOmers that are joined together by intermolecular H bonds and C-H.... л interactions in 2 and by only C-H.... л interactions in 3. A weak antiferromagnetism (J = -1.96(2) cm-1) is observed in complex 1 due to its asymmetric nitrite bridging. Complexes 2 and 3 show very weak antiferromagnetic interactions (J = -0.089 and -0.096 cm-1, respectively) attributed to the presence of intermolecular H-bonding and C-H.... -1 interactions. The corresponding Cu(l) species produced by the electrochemical reduction of complexes 1 and 2 disproportionate to Cu° and Cu2+ whereas the reduced Cu(l) species of complex 3 seems to be stable presumably due to a higher tetrahedral distortion of the equatorial plane in 3 compared to that in 1 and 2. [ABSTRACT FROM AUTHOR]

Three new phosphonic acid ligands (4-tbutylphenyl phosphonic acid, 3,5-dimethylphenyl phosphonic acid, and diphenylmethylphosphonic acid) have been synthesized and employed in search of high molecularity iron(III) clusters. The cluster compounds are characterized by single crystal X-ray diffraction and magnetic measurements. The solvothermal reaction of FeCl3·6H2O with diphenylacetic acid and p-tbutylphenyl phosphonic acid resulted in an unprecedented dodecanuclear cluster [Fe12(μ2-O)4(μ3-O)4(O2CCHPh2)14(4-tbuPhPO3H)6](1) having a double butterfly like core structure. [Fe12(μ2-O)4(μ3-O)4(O2CPh)14(C10H17PO3H)6](2), another dodecanuclear cluster having core structure similar to 1, has been synthesized in a reaction between [Fe3O(O2CPh)6(H2O)3]Cl and camphylphosphonic acid in the presence of triethylamine at ambient condition. 3,5-Dimethylphenyl phosphonic acid on reacting solvothermally with an oxo-centered iron triangle [Fe3O(O2CCMe3)6(H2O)3]Cl gives a nonanuclear cluster [Fe9(μ3-O)4(O3PPh(Me)2)3(O2CCMe3)13](3) having icosahedral type core structure where three positions of the iron atoms have been replaced by phosphorus. Another nonanuclear [Fe9(O)3(OH)3(O3PCHPh2)6(O2CCMe3)6(H2O)9] (4), having a distorted cylindrical core structure, has been synthesized in a similar solvothermal reaction between [Fe3O(O2CCMe3)6(H2O)3]Cl and biphenylmethyl phosphonic acid. All compounds are characterized by IR spectra, elemental analysis, as well as single crystal X-ray analysis. Magnetic measurements for all the compounds reveal that there are antiferromagnetic interactions between the metal centers. [ABSTRACT FROM AUTHOR]

Abstract: Four 3d–4f heterometallic coordination polymers, [Cu3(IDA)6Ln2]·n(H2O) [IDA= iminodiacetate dianion; Ln=Gd, n =3 (1); Ln=Nd, n =6 (2); Ln=Sm, n =6 (3)] and [Cu(Cl)(NTA)Sm(H2O)6]·(ClO4)·(H2O) (4) [NTA=nitrilotriacetate trianion], have heen synthesized and characterized by single crystal X-ray diffraction analysis. Complexes 1–3 are isomorphous, showing a 3D coordination framework having tubular channels filled by lattice water molecules running parallel to the c axis. Whereas complex 4 is a 1D polymer of alternating copper and samarium ions connected by NTA, and the chains get involved in H-bonding interactions resulting in a 3D network. A low temperature magnetic study reveals ferromagnetic interactions for complex 1. Thermogravimetric and X-ray powder diffraction analyses of 1, 2 and 3 show that the covalently bonded 3D network remains almost unaffected after deaquation. [Copyright &y& Elsevier]

A series of metal-organic hybrid compounds were synthesized using two new phosphonic acids, pyridyl-4-phosphonic acid and p-xylylenediphosphonic acid (H2O3PCH2C6H4CH2PO3H2). The phosphonic acid ligands have been synthesized from their corresponding bromides following two different types of reactions. The reaction of pyridyl-4-phosphonic acid with three different divalent metal salts results in the formation of molecular structures of different dimensionality. The reaction of Cu(ll) with the phosphonic acid under hydrothermal conditions yields a three-dimensional (3D) open framework structure having the molecular formula (Cu4(NC5H4-PO3)4(H2O)10] (1). The reactions with Mn(ll) and Zn(ll) salts with the same phosphonic acid resulted in a two-dimensional layered and a dinuclear compound with molecular formulas [Mn3(NC5H4-PO3)4(H2O)6(ClO4)2] (2) and EZn2(NHC5H4-PO3H)2Cl4] (3), respectively. Compound 1 crystallizes in the triclinic crystal system having space group P1 with structural parameters a = 7.4564(15) Å, b = 9.1845(19) Å, c = 11.582(2) Å, α = 100.842(3)°, β = 104.303(3)°, γ = 94.774(3)°, and Z = 1. Compound 2 crystallizes in the triclinic crystal system, space group P1, with structural parameters a = 7.6871(14) Å, b = 10.576(2) Å, c = 14.470(3) Å, α = 81.340(3)°, β = 81.561(3)°, γ = 68.757(3)°, and Z = 2, whereas compound 3 crystallizes in a monoclinic crystal system with space group P2(1)/n. The structural parameters are as follows: a = 8.4969 (5) Å, b = 9.3911 (5) Å, c = 12.3779 (6) Å, β = 90.860(17)°, and Z = 4. The pyridylphosphonate ligand shows different ligation behavior toward the three divalent metal ions. On the other hand, p-xylylenediphosphonic acid on reaction with Co(ll) formed a 3D compound [Co2(O3PCH2C6H4CH2PO3)2-(H2O)2] (4) with a layered and pillared structure. Compound 4 crystallizes in an orthorhombic crystal system with space group Pnma. The structural parameters are a = 21.744(4) Å, b = 5.6744(10) Å, c = 4.7927(9) Å, and Z = 4. [ABSTRACT FROM AUTHOR]

Abstract: One 3D and one 2D μ1,5-dicyanamide bridged NiII complexes having molecular formula [Ni(L1)(dca)2] (1) and [Ni2(L2)2(dca)4]·0.5H2O (2) (L1=4-(2-aminoethyl)-morpholine, L2=1-(2-aminoethyl)-piperidine and dca=dicyanamide dianion) have been synthesized. X-ray single crystal analyses and low temperature magnetic measurements were used to characterize the complexes. Complex 1 represents a 3D structure where each metal ion is chelated by morpholine ligand (L1) and connected by four μ1,5-dca. Whereas complex 2 shows an undulated 2D structure with grid of (4,4) topology having two crystallographically independent NiII centers in similar octahedral environment where each metal center is chelated by one piperidine ligand (L2) and coordinated by four μ1,5-dca. Magnetic measurements of both the complexes indicate weak antiferromagnetic interactions through the μ-1,5-dca bridging ligands. [Copyright &y& Elsevier]

One 2D and one 3D dicyanamide bridged complexes, [Cu(dca)2(et2-en)]n (1) and [Mn(dca)2(im)2]n (2) [dca=dicyanamide, et2-en=N,N-diethyl-ethylenediamine, im=imidazole], have been synthesized. Both the complexes are 1D by covalent bonding but interchain H-bonding promotes dimensionality. Moreover, π–π interaction among the imidazole ligands also plays an important role to have an interlocked 3D structure for 2. Magnetic study of both the complexes shows weak antiferromagnetic interaction between the metal centers. The magnetic data have been fitted with appropriate equations yielding best fit parameters for 1: J=-0.58±0.02 cm-1, g=2.11±0.01 with R=3.2×10-6 and for 2, J=-0.21 cm-1, g=2.00 and R=5.6×10-4. [Copyright &y& Elsevier]

Four new 3D supramolecules of Co(II), [cis-Co(H2O)4(fum)]n(H2O)n (violet) (1); [trans-Co(H2O)4(fum)]n (pink) (2); [Co(H2O)4(bpy)]n(fum)n(4H2O)n (pink) (3) and [Co(H2O)6(fum)(hmt)2·4H2O]n (pink) (4) [fum=fumarate, bpy=4,4′-bipyridine, hmt=hexamethylenetetramine, also known as urotropine] have been synthesized and characterized by X-ray single crystal structure determination, IR, electronic spectra and thermogravimetric analyses. Complexes 1 and 2 are obtained as a mixture from the same reaction. Structure analyses show that they consist of &z.sbnd;Co(H2O)4&z.sbnd;fum&z.sbnd; coordination polymers with carboxylate connected in a bis-monodentate fashion with a cis-(1) and trans-(2) geometry around Co(II). Both the compounds show strong intrachain as well as interchain hydrogen bonding interactions between the uncoordinated oxygens of the dicarboxylate and the coordinated water molecules to produce 3D supramolecular networks. Complex 3 gives likewise origin to a hydrogen bonded 3D framework, comprising of 1D &z.sbnd;Co(H2O)4&z.sbnd;(bpy)&z.sbnd; coordination chains with encapsulated fumarate and lattice water molecules. The structure of compound 4 comprises of Co(H2O)6 2+ and fumarate ions, hmt, and water molecules, all connected through an extensive hydrogen bonding to form a 3D network. All the complexes upon heating lose water molecules yielding blue species, which revert the process on exposure to humid atmosphere. [Copyright &y& Elsevier]

Focuses on the syntheses, structural analyses and magneto-structural correlations of three polymeric comlpexes with azide ligand. Structure description of the complexes; Magnetic properties; Crystallographic data collection and refinement.

Two novel inorganic-organic hybrid 3D extended networks of Ni(II) and Mn(II) having molecular formulas [(maleate)[sub 2]Ni[sub 3](bpe)[sub 4](H[sub 2]O)[sub 4]](NO[sub 3])[sub 2]·H[sub 2]O (1) and [(adipate)Mn(bpe)] (2) (bpe = 1,2-bis(4-pyridyl)ethane), respectively, have been synthesized and characterized by single-crystal X-ray diffraction studies and low-temperature (300-2 K) magnetic measurements. Compound 1 crystallizes in the monoclinic system, space group C2/c (No. 15), with chemical formula C[sub 56]H[sub 62]N[sub 10]Ni[sub 3]O[sub 19], a = 30.955(4), Å, b = 12.705(3) Å, c = 17.058(5) Å, β = 117.26(2)°, and Z = 4. Compound 2 crystallizes in the triclinic system, space group P&1macr; (No. 2), with chemical formula C[sub 18]H[sub 20]MnN[sub 2]O[sub 4], a = 8.492(2) Å, b = 9.444(2) Å, c = 11.533(3) Å, α = 97.19(1)°, β = 94.64(1)°, γ = 105.02(1)°, and Z = 2. The structure determination reveals for both a 3D network. Compound 1 contains two crystallographically independent Ni(II)ions in different octahedral environments. Ni(1)lies on an inversion center, and its coordination environment comprises two chelating maleate anions and two bpe nitrogen donors, while the Ni(2) ion is surrounded by meridionally disposed three bpe N atoms, two water molecules, and one oxygen donor from the dicarboxylate anion. Of the three crystallographic independent bpe ligand, one presents an anti and the others a gauche conformation. The corresponding N-to-N distances are 9.344, 6.543, and 6.187 Å. Variable-temperature magnetic susceptibility measurement of the complex reveals the existence of a dominant ferromagnetic interaction within the molecule. Compound 2 is composed of Mn[sub 2] dimer units linked by adipate anions to form corrugated 2D sheets which, on interconnection through bpe (anti conformation, N-to-N distance of 9.391 Å), produces an interpenetrated 3D &alpha... [ABSTRACT FROM AUTHOR]

Two new metal-organic based polymeric complexes, [Cu[sub 4](O[sub 2]CCH[sub 2]CO[sub 2])[sub 4](L)]·7H[sub 2]O (1) and [Co[sub 2](O[sub 2]CCH[sub 2]CO[sub 2])[sub 2](L)]'· 2H[sub 2]O (2) [L = hexamethylenetetramine (urotropine)], have been synthesized and characterized by X-ray crystal structure determination and magnetic studies. Complex 1 is a 1D coordination polymer comprising a carboxylato bridged Cu[sub 4] moiety linked by a tetradentate bridging urotropine. Complex 2 is a 3D coordination polymer made of pseudo-two-dimensional layers of Co(II) ions linked by malonate anions in syn-anti conformation which are bridged by bidentate urotropine in trans fashion. Complex 1 crystallizes in the orthorhombic system, space group Pmmn, with a = 14.80(2) Å, b = 14.54(2) Å, c = 7.325(10) Å, β = 90°, and Z = 4. Complex 2 crystallizes in the orthorhombic system, space group Imm2, a = 7.584(11) Å, b = 15.80(2) Å, c = 6.939(13) Å, β = 90.10°(1), and Z = 4. Variable temperature (300-2 K) magnetic behavior reveals the existence of ferro- and antiferromagnetic interactions in 1 and only antiferromagnetic interactions in 2. The best fitted parameters for complex 1 are J = 13.5 cm[sup -1], J' = -18.1 cm[sup -1], and g = 2.14 considering only intra-Cu[sub 4] interactions through carboxylate and urotropine pathways. In case of complex 2, the fit of the magnetic data considering intralayer interaction through carboxylate pathway as well as interlayer interaction via urotropine pathway gave no satisfactory result at this moment using any model known due to considerable orbital contribution of Co(II) ions to the magnetic moment and its complicated structure. Assuming isolated Co(II) ions (without any coupling, J = O) the shape of the χ[sub M]T curve fits well with experimental data except at very low temperatures. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks, molecular encapsulation, photocatalysis, proton conductivity, sensing, terpyridine-MOFs Frontispiece: Terpyridine-Based 3D Metal-Organic-Frameworks: A Structure-Property Correlation Keywords: metal-organic frameworks; molecular encapsulation; photocatalysis; proton conductivity; sensing; terpyridine-MOFs EN metal-organic frameworks molecular encapsulation photocatalysis proton conductivity sensing terpyridine-MOFs 1 1 1 04/05/21 20210401 NES 210401 B 4'-Phenyl terpyridine derivatives b are the main constituent of many interesting 3D metal-organic frameworks (MOFs), which show some excellent photophysical and materials properties. [Extracted from the article]

The research progress on 3D Prussian blue analogues (PBAs) and their successful downsizing using capping ligands to achieve 2D, 1D, and even discrete molecular analogues has greatly enhanced our understanding of the switchable phenomena such as spin crossover (SCO) and electron transfer coupled spin transition (ETCST) in these systems. These molecules exhibit diverse optical and magnetic properties, making them highly attractive for next-generation compact smart devices. However, better control over switchability is necessary to fulfil specific purposes. While substantial work over the past three decades has elucidated the rationale behind ETCST occurrence in some complexes but not in others, parallel investigations into the peculiar ETCST behaviour in response to subtle changes in ligand field, reaction conditions, and guest molecule size have provided improved control over parameters like H-bonding and π⋅⋅⋅π interactions. Efforts to increase the operational temperature range for chemical, thermal, piezo, and photo-responsive switchability of these molecules to practical levels and preserve their pristine properties after integration into devices require further exploration to unlock the optimisation possibilities. This review discusses factors affecting various stimuli-responsive ETCST behaviour in both solid (ligand field strength, lattice solvents, counter-ions and crystal packing) and solution phases (solvent polarity and protonation/deprotonation) with representative examples. We envisage that a better understanding of the factors controlling ETCST properties will enable precise design and targeted synthesis of these molecules. [Display omitted] • Magnetic switchability in [Fe-Fe] and [Fe-Co] PBAs. • Electron transfer sensitivity to primary and secondary coordination environments. • Chemical modification of organic ligands for thermal and optical bistability. • Secondary interactions in tuning the redox potential of metal ions. • Understanding of magnetic and electronic properties to integrate in smart devices. [ABSTRACT FROM AUTHOR]

Two novel mixed-valent manganese (MnII/MnIII) cluster compounds were synthesized in solvothermal reactions and characterized by single-crystal X-ray diffraction, bond valence sum calculations, IR spectra, elemental analysis, and magnetic measurements. Compound 1 is a Mn19 cluster with a cylindrical core structure. Compound 2 possess a Mn16 core where all of the manganese sites have unique ligation environments. The magnetic measurements on both compounds indicate dominant antiferromagnetic interactions between the metal centers. [ABSTRACT FROM AUTHOR]