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The synthesis and characterization of hexanuclear, octanuclear, and decanuclear manganese metalladiazamacrocycles of a series of pentadentate ligands with systematically controlled beta-branched N-acylsalicylhydrazides and alpha-branched N-acylsalicylhydrazides are reported. The results show that the size and shape of the substituents influence the nuclearity and the features of metalladiazamacrocycles because close contacts are occurring between the N-acyl substituents.

A trinuclear copper complex [Cu3(napxshz)2(phen)2] has been synthesised using a tribasic naproxen‐appended ligand [H3napxshz = 2‐hydroxy‐N′‐(2‐[6‐methoxynaphthalen‐2‐yl] propanoyl) benzohydrazide] and 1,10‐phenanthroline. The complex was characterised by different spectroscopic methods such as Fouriertransform infrared (FT‐IR), ultraviolet‐visible (UV–Vis) and electrospray ionisation (ESI)‐mass spectroscopy. The solid‐state structure of the ligand and complex 1 was established by single‐crystal X‐ray diffraction analysis. The interaction of the complex and the ligand with DNA was investigated by UV–visible spectroscopy and fluorometric titrations. The calculated binding constants (Kb) of the complex and the ligand with ct‐DNA show that the complex has a higher binding affinity than the ligand H3napxshz. Quantum chemical calculations were performed to understand the structural aspects of the complex and its interactions with DNA. The molecular docking study reveals the interaction between DNA, and the complex is in intercalative mode. [ABSTRACT FROM AUTHOR]

A manganese-based coordination polymer, [Mn2L2(µ-MeOH)2]n (H2L = 2-hydroxy-1-naphthaldehyde isonicotinoylhydrazone) was obtained by self-assembly of 2-hydroxy-1-naphthaldehyde isonicotinoylhydrazone and manganese(II) acetate. The coordination polymer was characterized by IR, EPR and UV–Vis spectroscopy. The single-crystal X-ray diffraction study reveals that the dibasic tridentate ligand (L2−) is bound via ONO donor sites to manganese(II). Two such [ML] fragments are connected by µ2-bridged methanol (MeOH) to form a di-manganese species. The sixth site of each of the manganese is occupied by the pyridyl N atom of the isonicotinoyl group. This arrangement gives a polynuclear complex of the formula [Mn2L2(µ-MeOH)2]n. The coordination geometry of manganese is distorted octahedral. The X-band electron paramagnetic resonance (EPR) measurement of the complex at 77 K shows a six-line spectrum and a signal at the half field, with g = 4.88. The half-field signal indicates the dimeric nature of the complex in the solution state. The cyclic voltammetric measurement of the complex shows a reversible MnIII/MnII redox couple. The complex catalyzes the conversion of 3,5-di-tert-butyl catechol to the corresponding o-quinone with a catalytic turnover rate of (kcat) 27.22 h−1. [ABSTRACT FROM AUTHOR]

A manganese ion and a ditopic pentadentate ligand were used to self-assemble either an [S.sub.8] symmetrical 48-membered hexadecanuclear or an [S.sub.10] symmetrical 60-memebred icosanuclear manganese metallamacrocycle. The icosanuclear manganese metallamacrocycle was observed to have a remarkable toroidlike shape with a relatively large internal hydrophobic cavity and hence could be considered as a new donut-shaped host to accommodate small organic molecules.

The preparation of discrete metal-organic polyhedra (MOP) with nanosized cavities by combining triangular C3-symmetric facial ligands and a potential hexatopic Cu(II) ion is discussed. Findings reveal that the nitrate anion results in 2-fold interpenetrating MOFs with an augmented primitive 3-D cubic network topology.

The construction of a new chiral pentadecanuclear metallamacrocycle using a pentadentate bridging ligand is described. The cyclic system is found to exhibit a sextuple twisted Mobius topology.

A study reports the synthesis of a new [S.sub.4]-symmetric icosanuclear manganese metalladiazamacrocycle using a pentadentate ligand, N-3-phenyl-trans-2-propenoylsalicylhydrazide ([H.sub.3]L), that has a rigid and bulky terminal N-acyl group. It is found that a 20 cyclic repeat of an -(Mn-N-N)-linkage results in a highly puckered diaza-bridged 60-membered icosanuclear metallamacrocycle.

Suitable designed C3-symmetric facial ligands and C4-symmetric metal ions are used as a general strategy for the preparation of face-driven corner-linked truncated octahedral nanocages. The cavity size and the port size of the cage can be controlled depending on the size of the facial ligands, which offers possibilities of developing suitable nanosized host systems that can accommodate suitable small molecular guests or chiral catalysts.

Abstract: Phase behavior of sodium oleate (NaOl)/isoamyl alcohol‐based lamellar gel phase in cedar oil/water medium in the presence of the nonionic polymer hydroxyethyl cellulose (HEC) and its hydrophobic modified product (HMHEC) is investigated for the development of polymer‐embedded surfactant gels. HMHEC is more soluble in oil‐in‐water (o/w) microemulsions, but nonionic HEC shows limited solubility in the lamellar microemulsion (o/w type). Quantitative estimation of rate of adsorption of the polymer on lamellae bilayers can be easily done by Sudan solubilization and methylene blue complexation methods. Addition of HMHEC to the lamellar gel phase increases the polymer solubilization limit of lamellar gels as well as the viscoelasticity and thermal stability. The polymer‐embedded microemulsion gel acts as a “clean gel” since it exhibits good solubilization in different hydrocarbon media at ambient conditions. Elastic modulus of the polymer‐embedded gel influences directly the suspension performance of gels at high temperature and yields a reasonable sand‐settling velocity acceptable according to fracturing standards. The thermal characteristics and viscoelastic properties of polymer‐embedded gel were found to be suitable for moderate‐temperature reservoir stimulation where the bottom hole temperature is in the range 70–75 °C. Already a large amount of experimental data on pure microemulsions (without polymer) exists. Our studies indicate that the developed polymer‐embedded microemulsion gel has great potential as a model system for the study of polymer–microemulsion interactions. [ABSTRACT FROM AUTHOR]

A Pd6L8 type coordination driven self-assembly was constructed using a tripodal ligand L (L = N1,N3,N5-trimethyl-N1,N3,N5-tris[(pyridin-4-yl)methyl]-1,3,5-benzene tricarboxamide) and palladium nitrate. The self-assembly was fully characterised using one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance spectroscopy, electrospray ionization-mass spectroscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy and elemental analysis. Use of high resolution transmission electron microscopy (HR-TEM) analysis confirms the discrete nature of the assembly with a dimension of ∼2.8 nm, consistent with the density functional theory optimised structure. The assembly acts as an efficient homogeneous catalyst for a copper and phosphine free Sonogashira reaction under mild and aerobic conditions in aqueous medium. The catalyst shows equal efficiency for both electron deficient and electron rich aryl iodides and bromides and is also suitable for use with aliphatic alkynes. The utility of the catalyst as a reusable heterogeneous catalyst in toluene was assessed up to the 3rd cycle without any significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

A detailed study has been done on the rheological properties of sodium oleate based hydrogels that are developed in the presence of organic and inorganic salts. Shear stability of the NaOL gels were found to be a strong function of the salt, alkali, and the fabrication conditions. The addition of alkali to NaOL/KCl hydrogel enhanced the viscoelastic properties, which were observed from static and dynamic rheological tests. The hydrogel is miscible with hydrocarbon and can act as a clean gel during a postfracturing job. The quantitative estimation of migration of NaOL to microemulsion medium during gel break test can be done by Sudan dye solubilization and Methylene blue complexation methods, and the results show that the addition of both KCl and NaOH favors NaOL micelle growth and its partitioning tendency toward the hydrocarbon phase. [ABSTRACT FROM AUTHOR]

A supramolecular compound, catena-poly{[Cu2(1,3-μ2-(1 a))2(μ2-ter)2(H2O)2] n·(6H2O) n} (1) has been synthesized using (1 a) [(1 a = N1, N3, N5-trimethyl- N1, N3, N5-tris((pyridin-4-yl)methyl)-1,3,5-benzene tricarboxamide] and terephthalate (ter) as the pillaring unit by self-assembly. The terephthalate units are connected by copper(II) ions forming a single strand, while a pair of such strands are then linked by (1 a) via two pyridyl terminal arms bound to copper(II) nodes on either side forming a one-dimensional double stranded assembly propagating along the c axis. The compound crystallizes in the Fdd2 space group. The cavity created in the interior of this double strand assembly trap six water molecules and are stabilized by hydrogen bonding with the host. The arrangement of the pair of acyclic water trimers in isolated cavities of (1) is such that it resembles a closed-bracket-like formation. The Hirshfeld surface analysis of (1) reveals the presence of strong intermolecular hydrogen-bonding interactions between one-dimensional ladder-like units and with the water trimer in the host cavity. The copper(II)-containing coordination polymer also acts as an efficient catalyst for the Glaser-Hay homo-coupling reaction. [ABSTRACT FROM AUTHOR]

Metalladiazamacrocycles, coordination driven potential supramolecular host systems, can be obtained via cyclic linkages of the metal ions and the bridging ligands, N-acylsalicylhydrazides. The nuclearity and the shape of the metallamacrocycles could be modulated by controlling the steric interactions caused by N-acyl tails of the ligands. The macrocycles could be utilized for recognition of small organic guest molecules using their hydrophobicity/hydrophilicity, the size and shape/symmetry of the cavities. In addition, these macrocycles can be used as the supramolecular building blocks for the construction of systematically tuned metal-organic frameworks since these clusters have several replaceable solvent sites which could serve as connecting nodes for the formaton of network structures. [ABSTRACT FROM AUTHOR]

Abstract: A three-dimensional supramolecule of [Cu(3,2,3-tet)] n {[Ag2(CN)4]} n (1), (3,2,3-tet = N,N′-bis(3-aminopropyl)ethylenediamine), in which [Cu(3,2,3-tet)]2+ cations are suspended in the two-dimensional anionic networks composed of [Ag2(CN)4]2+ building blocks, was synthesized and characterized by X-ray crystallography. Every silver(I) ion is five-coordinated including the silver–silver interaction in anionic network. Variable temperature magnetic susceptibility data indicate weak antiferromagnetic interaction (−0.378cm−1) between copper(II) ions in 1. [Copyright &y& Elsevier]

Hexanuclear, octanuclear, and decanuclear manganese metalladiazamacrocycles have been prepared by reacting a series of pentadentate ligands, N-acylsalicylhydrazides (N-(3-methylbutanoyl)salicylhydrazide (H33-mbshz), N-(phenylacetyl)salicylhydrazide (H3pashz), N-(3,3-dimethylbutanoyl)salicylhydrazide (H33-dmbshz), N-(2-methylpropanoyl)salicylhydrazide (H32-mpshz), N-((R,S)-2-methylbutanoyl)salicylhydrazide (H3RS-2-mbshz), N-((S)-2-methylbutanoyl)salicylhydrazide (H3S-2-mbshz), and N-(2,2-dimethylpropanoyl)salicylhydrazide (H32-dmpshz)), with manganese(II) acetate tetrahydrate. The self-assembled, supramolecular complexes assume a nearly planar cyclic structure with an -(Mn-N-N)n backbone and measure ∼2.1, ∼2.3, and ∼2.6 nm in outer diameters for n = 6, 8, and 10, respectively. The chiralities of the manganese centers on the metalladiazamacrocycle occur in alternating ⋯ΛΔΛΔ⋯ configurations. While β-branched N-acylsalicylhydrazides (H33-mbshz, H3pashz, H33-dmbshz) with a sterically flexible Cα methylene group yield 18-membered hexanuclear manganese metalladiazamacrocycles of S6 point group symmetry, α-branched N-acylsalicylhydrazides lead to 24-membered octanuclear manganese metalladiazamacrocycles or 30-membered decanuclear manganese metalladiazamacrocycles depending on the size of the N-acyl substituents. The α-branched H32-mpshz ligand with the sterically least demanding isopropyl tail at the N-acyl position yields a 24-membered octanuclear manganese metalladiazamacrocycle of S8 point group symmetry, but other α-branched N-acylsalicylhydrazides such as H3RS-2-mbshz, H3S-2-mbshz, and H32-dmpshz lead to 30-membered decanuclear manganese metalladiazamacrocycles of S10 point group symmetry. The magnetic properties of the metalladiazamacrocycles are characterized by a weak antiferromagnetic exchange interaction, with Jeff = -8.5 to -3.8 K between the Mn3+ ion spins with S = 2 in the cyclic system. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of tridentate ONS donor ligands H2L1, H2L2 and H2L3 (H2L1 =2-hydroxyacetophenone hexamethyleneimine-3-thiosemicarbazone; H2L2 =2-hydroxyacetophenone morpholine-3-thiosemicarbazone; H2L3 =2-hydroxyacetophenone N(4)-methyl, phenyl thiosemicarbazone) with Mn(OAc)2 ·4H2O afforded manganese(IV) complexes of the type [MnL2] in an ethanol–methanol mixture under air. The crystal structure of Mn(L2)2 ·0.25H2O reveals an octahedral geometry with the ligand coordinated in a meridional fashion. The molecule is packed in the crystal lattice with extended hydrogen bonding networks. EPR spectra of the complexes in frozen solution at 77K show a weak signal at g ≈4 and a strong sextet at g ≈2 consistent with manganese(IV) in an octahedral environment. Cyclic voltammetry in DMSO/ dichloromethane show quasi-reversible peaks corresponding to the Mn(IV)/Mn(III) redox couple. [Copyright &y& Elsevier]

An interesting series of eight neutral ternary Co(III) complexes of 2-hydroxyacetophenone N(4)-substituted thiosemicarbazones (H2L), bidentate heterocyclic bases 2,2′-bipyridine (bipy)/1,10-phenanthroline (phen) and azide with a general formula [MLB(N3)] were prepared. The complexes were characterized by means of spectroscopic methods. The coordination geometry around Co(III) in all the complexes is distorted octahedral with one dibasic tridentate ligand L2−, one bidentate heterocyclic base and one terminally coordinated azide group. Crystal structure of the compound CoL4bipyN3 was completely solved. All the electronic transitions were assigned. All complexes were diamagnetic indicating cobalt in a d6 strong field. [Copyright &y& Elsevier]

Discusses the coordination chemistry of thiosemicarbazones, due to their interesting physicochemical and biological properties. Means in which the thiosemicarbazones act as chelating ligands with copper (II) ion; Arrangement of two inversion-symmetry-related monomers; Coordination of the azomethine nitrogen atom to the central copper (II) ion.

A coordination driven Pd2LIG4 self-assembly is synthesized using a new semi rigid dipodal ligand. [ABSTRACT FROM AUTHOR]

In the title centrosymmetric binuclear complex, [V2(C17H17N4S)2O4], pairs of V atoms are linked by two oxo bridges. The coordination geometry at each VV atom is distorted octa­hedral, involving a pyridine N atom, a thiol­ate S atom, an azomethine N atom from the 1-[phen­yl(2-pyrid­yl)methyl­ene]-2-(pyrrolidin-1-ylthio­carbon­yl)hydrazine(−) ligand, and one terminal O and 2 bridging O atoms. The crystal structure is stabilized by weak inter­molecular C—H⋯O inter­actions. [ABSTRACT FROM AUTHOR]

A novel chemo-sensor based on diaminobenzidine (H 2 L) was synthesized and characterized. The chemo-sensor shows selective “turn-on” fluorescence response to Zn 2+ ion over a variety of other competing metal ions such as Al 3+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , and Cd 2+ . The strong fluorescent emission can be observed even at ppm level concentration of the probe in the presence of Zn 2+ with over 54 fold intensity enhancement at 509 nm. Similar fluorescence behaviour is also observed in a variety of solvents and solvent mixtures in the presence of zinc(II). The fluorescent emission is also detected when the H 2 L sample solution containing Zn 2+ is exposed to UV radiation. The sensitive nature of fluorescent response of the probe to Zn 2+ is gauged from the very low detection limit of 8.6 × 10 −9 M. The chemo-sensor H 2 L binds to zinc(II) in 1:1 stoichiometry as determined by Job's plot and the binding constant is calculated as 7.8 × 10 4 M −1 . [ABSTRACT FROM AUTHOR]

The article examines the utilization of the C3-symmetric facial ligands and C4-symmetric metal ions for the preparation of truncated octahedral nanocages. The curvature needed for truncation at the octahedral vertices was accomplished using ligands with a tilted pyridyl group and a nitrogen donor atom. The nanocages have 12 ports at the edges of the truncated octahedron.

Either an S 8 symmetrical 48-membered hexadecanuclear or an S 10 symmetrical 60-membered icosanuclear manganese metallamacrocycle was self-assembled using a manganese ion and a ditopic pentadentate ligand. This was either N-4-phenylbenzoylsalicylhydrazide (H 3pbshz) containing a rigid rod-shaped, bulky biphenyl residue as a terminal N-acyl group or N-3,3-diphenylpropionylsalicylhydrazide (H 3dppshz) containing a flexible beta-branched N-acyl group, but with two sterically bulky phenyl residues at the Cbeta position. The backbone of these metal-organic assemblies is a repeating unit consisting of a -[Mn-N-N-] link that extends to complete either the 48-membered cyclic structure involving 16 manganese(III) centers and 16 ditopic linker ligands or the 60-membered cyclic structure involving 20 manganese(III) centers and 20 ditopic linker ligands (depending on the ligand used). Even though the nuclearity of the metallamacrocycles was different, the successive manganese centers were in the same chiral sequence, ...(LambdaLambdaDeltaDelta)(LambdaLambdaDeltaDelta)....

An S6-symmetric hexanuclear gallium metalladiazamacrocycle, [Ga(III)(6)L2(6)S6] with a -(lamda delta)(lamda delta)-chiral sequence and an S-symmetric hexadecanuclear manganese metalladiazamacrocycle, [Mn(III)(16)L2(16)S16] with a -(lamda lamda delta delta)(lamda lamda delta delta)-chiral sequence were prepared using the same N2-trans-cinnamoyl-2-hydroxy-3-naphthoylhydrazide (H3L2) as a bridging pentadentate ligand between the metal centers for the formation of a macrocyclic system.

Two topologically different metallamacrocycles--S8 symmetric octanuclear gallium(III) metalladiazamacrocycle and pseudo-D4 symmetric octanuclear gallium(III) metalladiazamacrocycle--could be prepared using two similar heteroditopic bridging ligands having asymmetrical tridentate-bidentate binding residues.

Discrete metal-organic polyhedra (MOP) with nanosized cavities and/or clusters of MOP could be prepared when C3-symmetric facial ligands and a potential hexatopic Cu(II) ion are combined in the presence of perchlorate as a weak linker, while similar reaction conditions in the presence of a nitrate linker led to extended metal-organic frameworks made of MOP as supramolecular building blocks.

A novel S4-symmetric icosanuclear manganese metalladiazamacrocycle was synthesized using a pentadentate ligand, N-3-phenyl-trans-2-propenoylsalicylhydrazide (H3L), that has a rigid and bulky terminal N-acyl group. A 20 cyclic repeat of an--(Mn-N-N)--linkage resulted in a highly puckered diaza-bridged 60-membered icosanuclear metallamacrocycle. The steric interaction between the ligands in the cyclic system leads to five consecutive Mn(III) centers in a chemically different--(Mn(A)Mn(B)Mn(C)Mn(D)Mn(E))--environment, with the chiralities of the metal centers being in a rather complicated--(LambdaLambdaDeltaLambdaLambda)(DeltaDeltaLambdaDeltaDelta)--sequence.

An extended 36-membered dodecanuclear manganese metallamacrocycle with S12 symmetry has been synthesized using the ligand N-cyclohexanoylsalicylhydrazide (H3chxshz) by a self-assembly that accommodates a cyclooctane of conformationally strained S4 symmetry in its hydrophobic cavity.

The face-driven corner-linked truncated octahedral nanocages, [Pd6L8]12+ (1, L1 = N,N',N' '-tris(3-pyridinyl)-1,3,5-benzenetricarboxamide; 2, L2 = N,N',N' '-tris(4-pyridinylmethyl)-1,3,5-benzenetricarboxamide), were prepared with eight C3-symmetric tridentate ligands and six square planar tetratopic palladium(II) ions. The combination of the nitrogen donor atom at a approximately 120 degrees kink position of the carboxamido pyridinyl group and the tilted pyridyl versus the facial plane of the ligands can provide the needed curvature for the formation of octahedral cages. The nitrogen atoms can coordinate to the square planar palladium(II) ions to form kinks with approximately 120 degrees angles at the C4-symmetric square planar corners of the truncated octahedron. Depending on the conformation of the ligand, L1, two different truncated octahedral cages of around 2.4 nm in diameters were formed. The major form of 1 with syn-conformational ligands has a cavity volume of approximately 1600 A3. The cage has 12 ports (3.4 x 3.5 A2) at all edges of the octahedron. The minor form of cage 1 with anti-conformational ligands has a slightly increased cavity volume ( approximately 1900 A3) and port size (3.3 x 8.0 A2). The insertion of a methylene group in L2 has not only increased the cavity volume of 2 to approximately 2200 A3 but also enlarged the port size to 4.1 x 8.0 A2. However, an atomic force microscopy (AFM) study of cage 2 showed that the cages had a height of 1.8 +/- 0.1 nm. This value is about 30% smaller than the calculated size of 2.6 nm from the crystal structure. This tip-induced decrease in height in cage 2 suggests the nonrigidity of cage 2.

The title compound, [Cu2(C17H17N4S)2Cl2], exhibits a dimeric structure related by a centre of symmetry. The monomers are linked to each other by the longest Cu-S apical distance observed to date among Cu(II) square-pyramidal complexes of N4-substituted thiosemicarbazones. Each Cu(II) atom deviates from the coordination square plane, which contains the pyridyl and imine N atoms, the thiolate S atom and the Cl- anion, towards the S atom of the adjacent monomer. The dimers pack in a zigzag manner through the crystal.