Spin Crossover Quenching by "Racemization" in a Family of -1,2-Di(tetrazol-1-yl)cyclopentane-Based Fe(II) 1D Coordination Polymers.

Optically pure ()- and racemic (/)--1,2-di(tetrazol-1-yl)cyclopentane were synthesized and used to prepare homo- and heterochiral Fe(II) coordination compounds. [Fe((/)-CHN)(CHCN)](BF) (), [Fe((/)-CHN)(CHCN)](BF) (), [Fe(()-CHN)(CHCN)](BF)·2CHCN (), and [Fe(()-CHN)(CHCN)](BF) () form a family of one-dimensional coordination polymers. Fe(II) cations in these complexes are characterized by a heteroleptic coordination environment: the neighboring metal centers are bridged by two 1,2-di(tetrazol-1-yl)cyclopentane molecules, while the nitrile molecules (acetonitrile or propionitrile, respectively) occupy the axial positions.

Hexa- and octanuclear copper(II) complexes with a tetraeicosaaza amine macrocycle.

One hexa- and two octanuclear Cu(II) complexes were synthesised from different metal salts and a very large (8 + 8) tetraeicosaaza macrocycle. These nitrate, chloride and sulphate coordination compounds were characterised by taking elemental analysis, spectroscopy, crystallography and magnetic susceptibility measurements. Their crystal structures revealed different interesting coordination modes of Cu(II) cations and nuclearity in these centrosymmetric complexes.

Multinuclear Ni(II) and Cu(II) complexes of a 6 + 6 macrocyclic amine derived from -1,2-diaminocyclopentane and 2,6-diformylpyridine.

Four hexanuclear chloride and sulphate Ni(II) and Cu(II) complexes 1, 2, 4 and 5 and one tetranuclear nitrate Cu(II) complex 3 have been synthesised from appropriate metal salts and 6 + 6 octadecaaza macrocyclic ligands. All obtained coordination compounds have been characterised by elemental analysis, spectroscopic methods (ESI MS, NMR and EPR), magnetic susceptibility measurements and X-ray crystallography. Their X-ray crystal structures reveal different coordination modes of metal cations involved in the obtained centro-symmetrical coordination compounds.

Controlling chirality in the synthesis of 4 + 4 diastereomeric amine macrocycles derived from -1,2-diaminocyclopentane and 2,6-diformylpyridine.

A few suitably long dialdehyde and primary diamine building blocks of a predetermined chirality have been designed and synthesized to enable controlled and efficient synthesis of all six possible diastereomers of 4 + 4 macrocyclic amine derived from -1,2-diaminocyclopentane (DACP) and 2,6-diformypyridine (DFP) units. Although two out of six diastereomers have been reported recently, their synthesis presented here is more direct and occurs with an improved yield. This family of 4 + 4 macrocycles contains one pair of homochiral enantiomers of identical and configurations of DACP units, two different forms ( of alternating and of neighboring configuration of DACP moieties) as well as one pair of heterochiral enantiomers, where configuration of one diamine fragment is opposite to the other three diamine parts, and , respectively.

Mixed Macrocycles Derived from 2,6-Diformylpyridine and Opposite Enantiomers of trans-1,2-Diaminocyclopentane and trans-1,2-Diaminocyclohexane.

The condensation reaction of 2,6-diformylpyridine with an equimolar mixture of opposite enantiomers of trans-1,2-diaminocyclopentane and trans-1,2-diaminocyclohexane using a dynamic combinatorial chemistry approach has been examined. In nonmetal-templated reactions, depending on reaction conditions, mixed 2 + 1 + 1 macrocyclic imine or bigger mixed 4 + 2 + 2 imine macrocycle are formed selectively. The 2 + 1 + 1 imine used as a precursor in the templated by Cd ions produces a library of enlarged chiral mixed imines coordinated with metal cations among which the hexanuclear Cd complex of 6 + 3 + 3 imine was isolated and characterized.

Fully Conjugated [4]Chrysaorene. Redox-Coupled Anion Binding in a Tetraradicaloid Macrocycle.

[4]Chrysaorene, a fully conjugated carbocyclic coronoid, is shown to be a low-bandgap π-conjugated system with a distinct open-shell character. The system shows good chemical stability and can be oxidized to well-defined radical cation and dication states. The cavity of [4]chrysaorene acts as an anion receptor toward halide ions with a particular selectivity toward iodides ( K = 207 ± 6 M).

Hexanuclear and Trinuclear Metal Complexes of a Giant Octadecaaza Macrocycle.

A large macrocyclic ligand containing six pyridine fragments and six diaminocyclopentane fragments is able to form hexanuclear Zn(II) and Ni(II) complexes as well as a trinuclear Zn(II) complex. X-ray crystal structures of these complexes indicate quite different ligand conformations. In the hexanuclear Zn(II) derivative with chloride counteranions metal ions have a distorted-trigonal-bipyramidal geometry and occupy loop sections formed by the highly folded macrocycle, which adopts a globular shape.

Octulene: A Hyperbolic Molecular Belt that Binds Chloride Anions.

Octulene, the higher homologue of kekulene and septulene, was synthesized using the fold-in method. This new hydrocarbon macrocycle contains a large 24-membered inner circuit, which is peripherally fused to 24 benzene rings. Such an arrangement produces considerable hyperbolic distortion of the π-conjugated surface.

Multinuclear Ni(ii), Cu(ii) and Zn(ii) complexes of chiral macrocyclic nonaazamine.

The chiral macrocyclic amines R-L and S-L derived from the 3 + 3 condensation of 2,6-diformylpyridine and (1R,2R)-1,2-diaminocyclohexane or (1S,2S)-1,2-diaminocyclohexane form enantiopure trinuclear Ni(ii) and Cu(ii) complexes [Ni(L)(HO)Cl]Cl and [Cu(L)Cl]Cl and form the dinuclear complex [Zn(L)Cl](ZnCl) with Zn(ii). The X-ray crystal structures of these complexes indicate remarkably different conformations of the ligand and different binding modes of the chloride anions. The structure of the copper(ii) derivative [Cu(R-L)Cl]Cl·CHCN·7.

From 2 + 2 to 8 + 8 Condensation Products of Diamine and Dialdehyde: Giant Container-Shaped Macrocycles for Multiple Anion Binding.

The combination of 2,6-diformylpyridine and trans-1,2-diaminocyclopentane fragments results in 2 + 2, 3 + 3, 4 + 4, 6 + 6, and 8 + 8 macrocyclic imine condensation products. These imines can be reduced to the corresponding 2 + 2, 3 + 3, 4 + 4, 6 + 6, and 8 + 8 macrocyclic amines. The X-ray crystal structures of their protonated derivatives show a rich variety of macrocycle conformations ranging from a stepped 2 + 2 macrocycle to a multiply folded 8 + 8 macrocycle of globular shape.

Redox-Triggered Helicity Inversion in Chiral Cobalt Complexes in Combination with H(+) and NO3(-) Stimuli.

Three chiral ligands with variable denticity, H2L2-H2L4, conjugated by N,N'-ethylenebis[N-methyl-(S)-alanine] and an ortho-heterosubstituted aromatic amine, were newly synthesized as analogues of previously reported H2L1. Four contracted-Λoxo cobalt(III) complexes [Co(L)](+) with left-handed helical structure of Λ4Δ2 configuration were prepared by one-electron oxidation of the corresponding contracted-Λred cobalt(II) complexes [Co(L)], which were generated from chiral ligands and Co(ClO4)2·6H2O or Co(CF3SO3)2·5.2H2O in the presence of an organic base.

Lanthanide(III) and lead(II) complexes of a chiral nonaaza macrocyclic amine based on 1,2-diaminocyclopentane.

The macrocyclic nonaaza 3 + 3 amine based on diaminocyclopentane forms enantiopure helical complexes with lanthanide(III) ions. In contrast to analogous complexes based on 1,2-trans-diaminocyclohexane, no clear helicity process is observed. Crystal structures of these compounds show tight helical wrapping of the macrocycle around the lanthanide(III) ion leading to the formation of a double helix.

Stereoselective Wittig Olefination as a Macrocyclization Tool. Synthesis of Large Carbazolophanes.

Z-Selective Wittig olefination was applied to the synthesis of large carbazolophanes containing up to eight heteroaromatic subunits. A number of strategies were devised and tested, showing that cyclooligomerization yields can be significantly improved by using one-component schemes involving heterobifunctional reactants. [4]- and [6]Carbazolophanes were characterized in the solid state, revealing compact, highly folded structures.

Expansion of a 2 + 2 macrocycle into a 6 + 6 macrocycle: template effect of cadmium(II).

The reaction of trans-1,2-diaminocyclopentane with 2,6-diformylpyridine results in formation of 2 + 2, 3 + 3, and 4 + 4 Schiff base macrocycles as well as trace amounts of 6 + 6 and 8 + 8 macrocycles. In contrast, the 6 + 6 Schiff base macrocycle is a dominant product of the reaction of the isolated 2 + 2 macrocycle with excess of cadmium(II) chloride. The X-ray crystal structure of the protonated amine derivative of the 6 + 6 macrocycle reveals an unusual container-like conformation with the S6 axis.

Contrasting enantioselective DNA preference: chiral helical macrocyclic lanthanide complex binding to DNA.

There is great interest in design and synthesis of small molecules which selectively target specific genes to inhibit biological functions in which particular DNA structures participate. Among these studies, chiral recognition has been received much attention because more evidences have shown that conversions of the chirality and diverse conformations of DNA are involved in a series of important life events. Here, we report that a pair of chiral helical macrocyclic lanthanide (III) complexes, (M)-Yb[L(SSSSSS)](3+) and (P)-Yb[L(RRRRRR)](3+), can enantioselectively bind to B-form DNA and show remarkably contrasting effects on GC-rich and AT-rich DNA.

Helical lanthanide(III) complexes with chiral nonaaza macrocycle.

The chiral nonaazamacrocyclic amine L, which is a reduction product of the 3 + 3 Schiff base macrocycle, wraps around the lanthanide(III) ions to form enantiopure helical complexes. These Ce(III), Pr(III), Nd(III), Eu(III), Gd(III), Tb(III), Er(III), Yb(III) and Lu(III) complexes have been isolated in enantiopure form and have been characterized by spectroscopic methods. X-ray crystal structures of the Ln(III) complexes with L show that the thermodynamic product of the complexation of the RRRRRR-isomer of the macrocycle is the (M)-helical complex in the case of Ce(III), Pr(III), Nd(III) and Eu(III).

Lanthanide complexes of the heterochiral nonaaza macrocycle: switching the orientation of the helix axis.

The La(III), Ce(III), Pr(III), Nd(III), Sm(III), and Eu(III) complexes of the racemic heterochiral nonaaza macrocyclic amine L have been synthesized and characterized by spectroscopic methods. The X-ray crystal structures of the [PrL][Pr(NO(3))(6)].CH(3)OH and the isomorphic [NdL][Nd(NO(3))(6)].

Lanthanide complexes of the chiral hexaaza macrocycle and its meso-type isomer: solvent-controlled helicity inversion.

Lanthanide(III) complexes of the enantiopure chiral hexaaza tetraamine macrocycle L, 2(R),7(R),18(R),23(R)-1,8,15,17,24,31-hexaazatricyclo[25.3.1.

New 2+2, 3+3 and 4+4 macrocycles derived from 1,2-diaminocyclohexane and 2,6-diformylpyridine.

Two new Schiff base macrocycles - a 4+4 condensation product and a meso-type 2+2 condensation product - were obtained in a reaction of trans-1,2-diaminocyclohexane and 2,6-diformylpyridine. Reduction of these compounds led to the corresponding 4+4 and 2+2 macrocyclic amines. The macrocycles were characterised by NMR spectroscopy and electrospray mass spectrometry.