In the crystal structure of acenaphtho[1,2-b] pyrazine (or 7,10-diazafluoranthene), C14H8N2, the molecule has crystallographic m symmetry, but the observed symmetry is very close to mm2. The structure contains dimers of face-to-face antiparallel molecules.

The title molecule, C24H22O2, contains two planar naphthyl ring systems. The torsion angle around the the central C—C bond is 111.3 (2)° implying a transoid conformation with respect to the two ethoxy substituents. Only weak intermolecular interactions are present in the crystal structure.

A selection of donor–acceptor chromophores containing the redox-active dithiafulvene unit about acetylenic and aryl scaffolds has been synthesised. The molecules were studied for their optical, redox and structural properties. Moreover, third-order non-linear optical properties were investigated as a function of molecular structure.

A selection of tetrathiafulvalene (TTF) derivatives containing acetylenic moieties have been synthesized and studied by cyclic voltammetry and UV-Vis absorption spectroscopy. Ionization energy calculations on some extended TTFs were carried out employing the DFT method.

Tetrathiafulvalene (TTF) derivatives containing a diethynyl-substituted alkene spacer were synthesized and investigated for their electronic and structural properties. Co-planarity of the central diethynylethene unit and the two dithiole rings were confirmed by X-ray crystallographic analysis.

Manganese(II) complexes of mononegative pentadentate N4O ligands [Mn2(mgbpen)2(H2O)2](ClO4)2 (1), (mgbpen− = N-methyl-N′-glycyl-N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine) and [Mn2(bzgbpen)2(H2O)2](ClO4)2 (2), (bzgbpen− = N-benzyl-N′-glycyl-N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine) have been prepared. The crystal structure of the Mn(II)–aqua complex of 1, shows it to be dimeric via (μ-κO)-bridging through one carboxylate oxygen atom of each of the two ligands. The non-coordinated carboxylate oxygen atoms are H-bonded to the water ligands on the adjacent Mn ion. The magnetic coupling interaction is weak and antiferromagnetic, J = −1.3(1) cm−1. The dimeric structures of 1 and 2 are retained in solution and can exist in the gas phase. Complexes 1 and 2 are air stable but can be oxidised by tBuOOH to give unstable mononuclear Mn(III) complexes, or oxo-bridged dimanganese(III) and di-μ-oxo-dimanganese(IV) complexes, depending on solvent. The [Mn(III)–OR]+, R = H or CH3 complexes are generated in water or methanol, respectively, and are potentially useful spectroscopic models for active Mn–lipoxygenases. In acetonitrile, di-μ-oxo-dimanganese(IV) complexes are the highest oxidation state products detected, and these are formed via shorter-lived intermediate μ-oxo-dimanganese(III) compounds. The rate of formation of the various oxidized products is slower in the case of the bzgbpen− systems which contains a bulkier non-coordinating arm. The oxidised complexes were characterised by UV-visible spectroscopy, ESI mass spectrometry and cyclic voltammetry. In addition, III–IV and II–III species were electrochemically generated. Thus the new mononegative pentadentate ligand systems display significant flexibility in the range of Mn oxidation states and species of biological relevance that are accessible: A series of dinuclear compounds with different structures in the five oxidation levels between II–II and IV–IV has been identified. No solid state structures were obtained for high oxidation state species, however it is assumed that in the oxo-bridged compounds the carboxylate groups are terminally ligated in contrast to the starting Mn(II) complexes. Thus the system represents examples of limiting structures in the "carboxylate shift" mechanism proposed to be important in non-heme H2O and O2 activation processes.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Manganese(II) complexes of mononegative pentadentate N4O ligands [Mn2(mgbpen)2(H2O)2](ClO4)2 (1), (mgbpen− = N-methyl-N′-glycyl-N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine) and [Mn2(bzgbpen)2(H2O)2](ClO4)2 (2), (bzgbpen− = N-benzyl-N′-glycyl-N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine) have been prepared. The crystal structure of the Mn(II)–aqua complex of 1, shows it to be dimeric via (μ-κO)-bridging through one carboxylate oxygen atom of each of the two ligands. The non-coordinated carboxylate oxygen atoms are H-bonded to the water ligands on the adjacent Mn ion. The magnetic coupling interaction is weak and antiferromagnetic, J = −1.3(1) cm−1. The dimeric structures of 1 and 2 are retained in solution and can exist in the gas phase. Complexes 1 and 2 are air stable but can be oxidised by tBuOOH to give unstable mononuclear Mn(III) complexes, or oxo-bridged dimanganese(III) and di-μ-oxo-dimanganese(IV) complexes, depending on solvent. The [Mn(III)–OR]+, R = H or CH3 complexes are generated in water or methanol, respectively, and are potentially useful spectroscopic models for active Mn–lipoxygenases. In acetonitrile, di-μ-oxo-dimanganese(IV) complexes are the highest oxidation state products detected, and these are formed via shorter-lived intermediate μ-oxo-dimanganese(III) compounds. The rate of formation of the various oxidized products is slower in the case of the bzgbpen− systems which contains a bulkier non-coordinating arm. The oxidised complexes were characterised by UV-visible spectroscopy, ESI mass spectrometry and cyclic voltammetry. In addition, III–IV and II–III species were electrochemically generated. Thus the new mononegative pentadentate ligand systems display significant flexibility in the range of Mn oxidation states and species of biological relevance that are accessible: A series of dinuclear compounds with different structures in the five oxidation levels between II–II and IV–IV has been identified. No solid state structures were obtained for high oxidation state species, however it is assumed that in the oxo-bridged compounds the carboxylate groups are terminally ligated in contrast to the starting Mn(II) complexes. Thus the system represents examples of limiting structures in the “carboxylate shift” mechanism proposed to be important in non-heme H2O and O2 activation processes.

A general and efficient four-step synthesis of a tetrathiafulvalene-belt 6, starting from the monopyrrolo-tetrathiafulvalene building block 1, is described, together with its 7,7,8,8-tetracyano-p-quinodimethane charge transfer complex. The complexation of the electron acceptor 7,7,8,8-tetracyano-p-quinodimethane by the tetrathiafulvalene-belt 6 was investigated both in solution and in the solid state. [reaction: see text]

[reaction: see text] A novel type of tetrathiafulvalene-cage 4 containing three monopyrrolo-tetrathiafulvalene units has been prepared employing a general and efficient synthetic approach. X-ray crystal structure analysis revealed that the cage is able to accommodate solvent molecules within a cavity in the solid state.

A tricyclic nucleoside is synthesised from a bicyclic nucleoside precursor by applying a stereoselective dihydroxylation, a regioselective tosylation and an intramolecular ether formation. This tricyclic nucleoside is constructed as a conformationally locked thymidine analogue and has been analysed by X-ray crystallography. Thus, the furanose ring of this nucleoside adopts a perfect S-type conformation and the torsion angle gamma, describing the C4'-C5' bond is restricted in the +ac range. The tricyclic nucleoside is incorporated into two nonameric oligonucleotide sequences displaying strongly decreased affinity towards complementary DNA and RNA when compared to the corresponding unmodified oligodeoxynucleotide sequences.

The zinc(II) chloride catalysed reaction between ethylene trithiocarbonate (1) and dibenzoylacetylene (3) gave the novel 2,3,5,6-tetrabenzoylthiopyran-4-thione (4a) and its structure was elucidated by X-ray crystallography. Treatment of 2,3,5,6-tetrabenzoylthiopyran-4-chalcogenones (4a,b) with triethyl phosphite afforded the bis-annelated furans 1,3,5,7-tetraphenylthiopyrano[2,3-c:5,6-c']difuran-8-chalcogenones (5a,b) in almost quantitative yields. The mechanism for this furan formation is discussed.

The structures of the oxysubstituted triphenylene premesogens, 2,3,6,7,10,11-hexahydroxytriphenylene (4), 2,3,6,7,10,11-hexamethoxytriphenylene (5), 2,3,6,7,10,11-hexaethoxytriphenylene (6), and 2,3,6,7,10,11-hexapropoxytriphenylene (7) were determined, and the structural results were investigated in the aim that a detailed structural knowledge of the discotic premesogens could be used to infer detailed structural knowledge with respect to known liquid crystal mesogens where little detailed structural knowledge is available. It was found that the crystal structures of the discotic premesogens were very different from the structures expected for discotic columnar behavior. These differences allowed us to shed some light on the structural forces that gives rise to the mesophasic behavior observed in such systems as being not due to stacking of the planar aromatic core as inferred hitherto but rather governed by the alkyl groups.

The tris-tetrathiafulvalene (TTF) macrocycles 3 with a large end-cavity were effectively synthesized from the readily available tetrakis(cyanoethylthio)TTF by means of a selective deprotection/realkylation sequence followed by an intramolecular coupling reaction. Crystar structure analyses revealed that the neutral molecules include two (3a) or one chloroform molecule (3b) as solvent of crystallization inside the cavity, whereas the I3- salt of 3b, obtained by electrocrystallization, has a molecular structure which is different from that of the neutral molecule in that the cavity has completely collapsed.

The Mitsunobu reaction is shown to be a versatile method for the incorporation of pyromellitic diimide (PMDI) acceptors into new macrocyclic structures containing tetrathiafulvalene (TTF) donors. In the case of macrocycle 5, the more efficient bis-pyrroloTTF donor was used instead of TTF Macrocycle 1 revealed distinct charge-transfer interactions in the trans-configuration, but not in the corresponding cis-form. Depending on the spatial geometry, inter- and intramolecular interactions between the TTF-donor and the PMDI-acceptor take place. X-ray crystal structures of macrocycles 1-cis, 1-trans, 2 and 5 are reported.

The crystal structures of a charge-transfer complex of triphenylene with 1,3,5-tris(2,2-dicyanovinyl) benzene (1), a complex of 2,3,6,7,10,11-hexamethoxytriphenylene with 2,5-dichlorotetracyanoquinodimethane (2) and also 2,5-dichlorotetracyanoquinodimethane itself (3) have been determined. Compound 1 is triclinic, space group P (1) over bar, with a = 7.055(1), b = 11.026(2), c = 17.214(3) Angstrom. alpha = 96.59 (3), beta = 90.34(3), gamma = 91.61(3)degrees. Compound 2 is triclinic, space group P (1) over bar, with a = 12.228(2), b = 12.994(3), c = 13.702(3) Angstrom, alpha = 70.72(3), beta = 83.73(3), gamma = 66.06(3)degrees. Compound 3 is monoclinic, space group I2/a (C2/c), with a = 13.692(3), b = 7.7183(15), c = 16.391(3) Angstrom, beta = 99.47(3)degrees. The structures of 1 and 2 consist of mixed stacks of donors and accepters. The structures of 2 and 3 both include 1,2-dichlorobenzene solvent molecules. Weak hydrogen bonds are present in the structures of 1 and 2. Based on comparisons of bond lengths the electronic charge-transfer in 2 has been estimated to be about 0.3 e. The synthesis of 1,3,5-tris(2,2-dicyanovinyl) benzene is also reported.

The geometry of the 4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene system in the cationic state was established by X-ray structural resolution of the salts formed between the cation and various anions. The geometry was found to be planar for the 4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo [cd,mn]pyrenylium and 2,6,10-tri(tert-butyl)-4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrenylium cations with the monovalent anions I-, BF4-, PF6- AsF6-, HNO3. NO3- and CF3SO3-, and the divalent anions S2O62- and Mo6Cl142-. The salts were found to crystallize in distinct space groups following a characteristic pattern. Mixed cation-anion stacking resulted in space groups with high symmetry: Pbca in three cases and R (3) over bar c in one; a temperature study of the latter was made at ten different temperatures. The formation of dimers of anions and cations resulted in lower-symmetry space groups, mainly monoclinic (P2(1)/n, P2(1)/c and C2/c), but also P (1) over bar.

The synthesis of three novel macrocycles 3-5 based on the two electron donors bis(2,5-dimethylpyrrolo)[3,4-d]tetrathiafulvalene (1) and 1,4-hydroquinone is presented. Their abilities to include the electron acceptor paraquat (6) have been investigated by UV/Vis and H-1 NMR spectroscopy and an X-ray crystallographic analysis. Also, the complex formation between the cyclic acceptor cyclobis(paraquat-p-phenylene) (7) and different tetrathiafulvalene derivatives has been studied. A strong association between 1 and 7 facilitates the self-assembly of catenanes from the macrocycles 3-5. However, the preferred position of the cyclic acceptor 7 in the catenanes around either the pyrrolo-annelated TTF or around the hydroquinone donor relies on a fine balance between all the individual noncovalent forces acting in cooperation.

Efficient synthesis of a novel tetrathiafulvalene building block, 2,3-bis(2-cyanoethylthio)-6,7-bis(thiocyanatomethyl) tetrathiafulvalene (7) useful for stepwise and asymmetrical bis-functionalization is reported.