Solvent-Induced Structural Changes in Complexes of 1,2-Bis(3-(3-pyridyl)pyrazolyl)ethane

A series of complexes have been obtained using the flexible ditopic ligand 1,2-bis(3-(3-pyridyl)pyrazolyl)ethane (LEt) with M(SCN)2 (M = Co, Fe) and ZnCl2. The ligand is observed to exist in a variety of conformations with rotations around the ethane spacer and around the pyridyl/pyrazole bond. The bridging length of the ligand (i.e., distance between pyridyl nitrogen atoms) varies by 3.5 Å depending on its geometry. Three different cobalt(ii) complexes of the general form [Co(LEt)2(SCN)2]·Solv (where Solv is a variable number/type of non-coordinated solvent) have been structurally characterized and form a series of solvent dependant supramolecular isomers. When Solv = 2MeCN a (4,4)-sheet is formed (1), however, when Solv = H2O an alternate ‘collapsed’ (4,4)-sheet is observed (2). Changing the solvent to two molecules of N,N-dimethylformamide (DMF) leads to a radical change in structure with a one-dimensional (1D) polymer formed (3) that contains two bridging ligands between adjacent metal atoms (i.e., maintaining the same metal/ligand ratio as in the (4,4)-sheet structures). A monomeric thiocyanate complex [Fe(LEt)2(SCN)2(H2O)2] (4) is reported in which the bispyridyl ligands are terminal and partake in an extended hydrogen-bonded network. A 1D polymer [Zn(LEt)Cl2] (5) is also presented. The structures of the metal complexes are contrasted with that of the free ligand.

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Synthesis and Structural Characterization of (E)-4-[(2-Hydroxy-3-methoxybenzylidene)amino]butanoic Acid and Its Novel Cu(II) Complex

Molbank ◽

10.3390/m1179 ◽

2021 ◽

Vol 2021 (1) ◽

pp. M1179

Author(s):

Eleftherios Halevas ◽

Antonios Hatzidimitriou ◽

Barbara Mavroidi ◽

Marina Sagnou ◽

Maria Pelecanou ◽

...

Keyword(s):

Schiff Base ◽

Gamma Aminobutyric Acid ◽

X Ray Diffraction ◽

Reaction Conditions ◽

Polymeric Compound ◽

Bridging Ligands ◽

1H And 13C Nmr ◽

One Dimensional ◽

Ft Ir

A novel Cu(II) complex based on the Schiff base obtained by the condensation of ortho-vanillin with gamma-aminobutyric acid was synthesized. The compounds are physico-chemically characterized by elemental analysis, HR-ESI-MS, FT-IR, and UV-Vis. The complex and the Schiff base ligand are further structurally identified by single crystal X-ray diffraction and 1H and 13C-NMR, respectively. The results suggest that the Schiff base are synthesized in excellent yield under mild reaction conditions in the presence of glacial acetic acid and the crystal structure of its Cu(II) complex reflects an one-dimensional polymeric compound. The molecular structure of the complex consists of a Cu(II) ion bound to two singly deprotonated Schiff base bridging ligands that form a CuN2O4 chelation environment, and a coordination sphere with a disordered octahedral geometry.

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The Lithuanian Case of Higher Education Reforms in Europe

International Higher Education ◽

10.6017/ihe.2008.52.8027 ◽

2015 ◽

Author(s):

Liudvika Leisyte

Keyword(s):

Higher Education ◽

Structural Changes ◽

Bologna Process ◽

Radical Change ◽

The State ◽

European Countries ◽

Education Reforms ◽

Higher Education Reforms ◽

The Bologna Process

The Bologna process has spurred higher education reforms in various European countries. Higher education reforms in Lithuania took place rather incrementally and represented an interaction between two strong powersthe state and the academic oligarchy. In the 1990s, the structural changes at the forefront of the Bologna-related reforms in Lithuania, but higher education reforms have remained stagnant in Lithuania. It is too early to draw conclusions about the success of the reforms, but the involvement of various stakeholders and the vision of broad reforms increase hopes for prospects of a more radical change of the Lithuanian higher education landscape.

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A neutron diffraction study of structural changes in one-dimensional K2Pt(CN)4Br0.3 · 3H2O from 77–323°K

Solid State Communications ◽

10.1016/0038-1098(75)90331-2 ◽

1975 ◽

Vol 17 (1) ◽

pp. 45-48 ◽

Cited By ~ 25

Author(s):

J.M. Williams ◽

F.K. Ross ◽

M. Iwata ◽

J.L. Petersen ◽

S.W. Peterson ◽

...

Keyword(s):

Neutron Diffraction ◽

Diffraction Study ◽

Structural Changes ◽

Neutron Diffraction Study ◽

One Dimensional

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Influence of the Para-Substituent in Lanthanoid Complexes of Bistetrazole Substituted Calix[4]arenes

10.26434/chemrxiv.9255209 ◽

2019 ◽

Author(s):

Rene Z.H. Phe ◽

Brian Skelton ◽

Massimiliano Massi ◽

Mark Ogden

Keyword(s):

Structural Changes ◽

Cluster Formation ◽

Ammonium Cation ◽

Ammonium Salts ◽

X Ray Diffraction ◽

One Dimensional ◽

X Ray ◽

Mononuclear Complexes ◽

Scattering Measurements ◽

The Impact

5,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(tetrazole-5-ylmethoxy)calix[4]arene has been reported to form remarkable Ln19 and Ln12 elongated clusters, upon addition of aqueous ammonium carboxylates. The impact of the para substituent on lanthanoid cluster formation has been studied by synthesising two new bis-tetrazole calixarenes, with p-H, and p-allyl substituents. Solution phase dynamic light scattering measurements of the reaction mixtures indicated that clusters are not formed with the p-H and p-allyl derivatives, in contrast with the behaviour of the t-butyl analogue. Lanthanoid complexes of the p-H and p-allyl calixarenes were characterised by single crystal X-ray diffraction, and were found to form mononuclear complexes, linked to form a one-dimensional coordination polymer for the p-allyl system. All of the complexes were isolated as ammonium salts, with ammonium cation included in the calixarene cavity in most cases. It is concluded that the nature of the para substituent has a profound impact on the lanthanoid cluster formation process, and derivatives with more subtle structural changes will be required to determine if additional lanthanoid “bottlebrush” clusters can be isolated.

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Mixed Ca/Sr salt forms of salicylic acid: tuning structure and aqueous solubility

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229617018265 ◽

2018 ◽

Vol 74 (2) ◽

pp. 131-138 ◽

Cited By ~ 1

Author(s):

Pamela Allan ◽

Jean-Baptiste Arlin ◽

Alan R. Kennedy ◽

Aiden Walls

Keyword(s):

Salicylic Acid ◽

Coordination Polymer ◽

Single Crystal ◽

Structural Feature ◽

Structural Changes ◽

Aqueous Solubility ◽

Single Crystal Diffraction ◽

One Dimensional ◽

The One ◽

Salt Forms

Ten isostructural single-crystal diffraction studies of mixed cation Ca/Sr salt forms of the salicylate anion are presented, namely catena-poly[[diaquacalcium(II)/strontium(II)]-bis(μ2-2-hydroxybenzoato)], [Ca1–x Sr x (C7H5O3)2(H2O)2] n , where x = 0, 0.041, 0.083, 0.165, 0.306, 0.529, 0.632, 0.789, 0.835 and 1. The structure of an isostructural Sr/Ba species, namely catena-poly[[diaquastrontium(II)/barium(II)]-bis(μ2-2-hydroxybenzoato)], [Sr0.729Ba0.271(C7H5O3)2(H2O)2], is also described. The Ca/Sr structures form a series where, with increasing Sr content, the unit cell expands in both the crystallographic a and c directions (by 1.80 and 3.18%, respectively), but contracts slightly in the b direction (−0.31%). The largest percentage structural expansion lies parallel to the direction of propagation of the one-dimensional coordination polymer that is the primary structural feature. This structural expansion is thus associated with increased M—O distances. Aqueous solubility measurements show that solubility generally increases with increasing Sr content. Thus, tuning the composition of these mixed counter-ion salt forms leads to systematic structural changes and allows solubility to be tuned to values between those for the pure Ca and Sr species.

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Cyano-Functionalized Porphyrins on Cu(111) from One-Dimensional Wires to Two-Dimensional Molecular Frameworks: On the Role of Co-Deposited Metal Atoms

Chemistry of Materials ◽

10.1021/acs.chemmater.9b05256 ◽

2020 ◽

Vol 32 (5) ◽

pp. 2114-2122

Author(s):

Alisson Ceccatto dos Santos ◽

Rodrigo Cezar de Campos Ferreira ◽

Juan Carlos Moreno-López ◽

Lucas Barreto ◽

Michael Lepper ◽

...

Keyword(s):

Two Dimensional ◽

One Dimensional ◽

Metal Atoms ◽

Deposited Metal

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One-dimensional CuIIcoordination polymers containingC2h-symmetric 1,1′:4′,1′′-terphenyl-3,3′-dicarboxylate linkers

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229615017088 ◽

2015 ◽

Vol 71 (10) ◽

pp. 929-935 ◽

Cited By ~ 3

Author(s):

Hyun-Chul Kim ◽

Ja-Min Gu ◽

Seong Huh ◽

Chul-Hyun Yo ◽

Youngmee Kim

Keyword(s):

Coordination Polymers ◽

Three Dimensional ◽

Polymer Chains ◽

Water Molecules ◽

Binding Modes ◽

Bridging Ligands ◽

One Dimensional ◽

X Ray Crystallography ◽

Dimensional Network ◽

The One

Two new one-dimensional CuIIcoordination polymers (CPs) containing theC2h-symmetric terphenyl-based dicarboxylate linker 1,1′:4′,1′′-terphenyl-3,3′-dicarboxylate (3,3′-TPDC), namelycatena-poly[[bis(dimethylamine-κN)copper(II)]-μ-1,1′:4′,1′′-terphenyl-3,3′-dicarboxylato-κ4O,O′:O′′:O′′′] monohydrate], {[Cu(C20H12O4)(C2H7N)2]·H2O}n, (I), andcatena-poly[[aquabis(dimethylamine-κN)copper(II)]-μ-1,1′:4′,1′′-terphenyl-3,3′-dicarboxylato-κ2O3:O3′] monohydrate], {[Cu(C20H12O4)(C2H7N)2(H2O)]·H2O}n, (II), were both obtained from two different methods of preparation: one reaction was performed in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) as a potential pillar ligand and the other was carried out in the absence of the DABCO pillar. Both reactions afforded crystals of different colours,i.e.violet plates for (I) and blue needles for (II), both of which were analysed by X-ray crystallography. The 3,3′-TPDC bridging ligands coordinate the CuIIions in asymmetric chelating modes in (I) and in monodenate binding modes in (II), forming one-dimensional chains in each case. Both coordination polymers contain two coordinated dimethylamine ligands in mutuallytranspositions, and there is an additional aqua ligand in (II). The solvent water molecules are involved in hydrogen bonds between the one-dimensional coordination polymer chains, forming a two-dimensional network in (I) and a three-dimensional network in (II).

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Synthesis and Properties of a New Kind of One-Dimensional Conductors. 1. General Aspects

Zeitschrift für Naturforschung A ◽

10.1515/zna-1979-0810 ◽

1979 ◽

Vol 34 (8) ◽

pp. 983-985 ◽

Cited By ~ 18

Author(s):

Michael Hanack ◽

Friedrich Franz Seelig ◽

Joachim Strähle

Keyword(s):

Experimental Studies ◽

Bidentate Ligand ◽

Central Metal Atom ◽

Central Metal ◽

Bridging Ligands ◽

One Dimensional ◽

Bridging Ligand ◽

Linear Chains ◽

Square Planar ◽

General Aspects

AbstractA model for a new kind of one-dimensional conductors is presented. The compounds consist of square-planar metal complexes MX4 which are polymerised via bridging ligands L to linear chains. The bidentate ligand L, e.g. C22-, leads to the formation of a linear π-system along the chain, which is essential for the conductivity. The square-planar complex can be, for example, a metal phthalocyanine. MO-calculations show that this kind of polymer gives rise to a suitable energy band structure. An advantage of the new one-dimensional conductors is their flexibility; different combinations of the square-planar ligand system, the bridging ligand, and the central metal atom can be used. First experimental studies show that the preparation of the proposed conductors is possible.

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Thickness dimensions of the contact layer of soil-rigid body interaction

E3S Web of Conferences ◽

10.1051/e3sconf/20199704040 ◽

2019 ◽

Vol 97 ◽

pp. 04040 ◽

Cited By ~ 5

Author(s):

Bakhtiyar Khusanov ◽

Barno Rikhsieva

Keyword(s):

Rigid Body ◽

Structural Changes ◽

Soil Layer ◽

Contact Layer ◽

Interaction Process ◽

Soil Medium ◽

One Dimensional ◽

Underground Pipelines ◽

The Finite Difference Method ◽

Dimensional Statement

Solution of the problems of longitudinal interaction of underground pipelines with soil in a one-dimensional statement requires precise measurements of the thickness of the soil layer contacting with the pipeline. In order to determine the dimensions of the contact layer of soil, the behavior of soil medium under shear interaction of a rigid body with soil is studied. Under straining in soil medium, structural changes denoted by the coefficient of structural destruction are taken into account; the condition of complete adhesion is taken in the contact rigid body – soil boundary. The interaction process under consideration is investigated numerically by the finite difference method. The results of the calculations are presented in the form of graphs and are analyzed. From the obtained results, the maximum values of the thickness of soil contact layer are determined as well as the layers with the corresponding degree of structural destruction depending on the geometric dimensions of the rigid body.

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