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1.
Inorg Chem ; 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-32302124

RESUMO

Metal bis(1,2-dithiolene) complexes belonging to the class [Ni(Ar-edt)2]x- [Ar-edt2- = arylethylene-1,2-dithiolate; Ar = phenyl, (1x-), 2-naphthyl (2x-); x = 0 and 1] were fully characterized by NMR, UV-visible-near-infrared (UV-vis-NIR), diffuse reflectance, and FT-IR spectroscopy, as well as cyclic voltammetry and single-crystal X-ray diffraction analysis. These complexes have emerged as new photoconducting materials that allowed for the development of a prototype of photodetectors with response in the vis-NIR region. The photodetecting devices showed in some cases quantum efficiencies orders of magnitude higher than those of previously reported 1,2-dithiolene systems.

2.
Dalton Trans ; 44(13): 6219-23, 2015 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-25736841

RESUMO

The first radical-cation salts in the extensive family (BEDT-TTF)x[(A)M(C2O4)3]·Guest containing lithium as the counter cation have been synthesized and characterised.

3.
Chem Cent J ; 9(1): 1, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25649693

RESUMO

BACKGROUND: Structural systematics is the comparison of sets of chemically related crystal structures with the aim to establish and describe relevant similarities and relationships. An important topic in this context is the comparison of hydrogen-bonded structures (HBSs) and their representation by suitable descriptors. RESULTS: Three different description methods for HBSs are proposed, a graphical representation, a symbolic representation and connectivity tables. The most comprehensive description is provided by a modified graph of the underlying net topology of an HBS which contains information on the multiplicity of links, the directionality and chemical connectivity of hydrogen bonds and on symmetry relations. By contrast, the alternative symbolic representation is restricted to essential properties of an HBS, i.e. its dimensionality, topology type and selected connectivity characteristics of nodes. A comparison of their connectivity tables readily identifies differences and similarities between crystal structures with respect to the intermolecular interaction modes adopted by their functional groups. The application of these methods to the known polymorphs of sulfathiazole and sulfapyridine is demonstrated and it is shown that they enable the rationalisation of previously reported and intricate relationships. CONCLUSIONS: The proposed methods facilitate the comprehensive description of the most important relevant aspects of an HBS, including its chemical connectivity, net topology and symmetry characteristics, and they represent a new way to recognise similarities and relationships in organic crystal structures. Graphical AbstractGraphical Representation of mixing of structures StzIV and StzV to give structure StzIII.

4.
Chem Cent J ; 8(1): 70, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25516767

RESUMO

BACKGROUND: Derivatives of fulgides have been shown to have interesting photochromic properties. We have synthesised a number of such derivatives and have found, in some cases, that crystals can be made to change colour on crushing, a phenomenon we have termed "tribochromism". We have studied a number of derivatives by X-ray crystallography, to see if the colour is linked to molecular structure or crystal packing, or both, and our structural results have been supported by calculation of molecular and lattice energies. RESULTS: A number of 5-dicyanomethylene-4-diphenylmethylene-3-disubstitutedmethylene-tetrahydrofuran-2-one compounds have been prepared and structurally characterised. The compounds are obtained as yellow or dark red crystals, or, in one case, both. In two cases where yellow crystals were obtained, we found that crushing the crystals gave a deep red powder. Structure determinations, including those of the one compound which gave both coloured forms, depending on crystallisation conditions, showed that the yellow crystals contained molecules in which the structure comprised a folded conformation at the diphenylmethylene site, whilst the red crystals contained molecules in a twisted conformation at this site. Lattice energy and molecular conformation energies were calculated for all molecules, and showed that the conformational energy of the molecule in structure IIIa (yellow) is marginally higher, and the conformation thus less stable, than that of the molecule in structure IIIb (red). However, the van der Waals energy for crystal structure IIIa, is slightly stronger than that of structure IIIb - which may be viewed as a hint of a metastable packing preference for IIIa, overcome by the contribution of a more stabilising Coulomb energy to the overall more favourable lattice energy of structure IIIb. CONCLUSIONS: Our studies have shown that the crystal colour is correlated with one of two molecular conformations which are different in energy, but that the less stable conformation can be stabilised by its host crystal lattice. Graphical abstractGraphical representation of the structural and colour change in the tribochromic compound (III).

5.
Chemistry ; 20(4): 1081-90, 2014 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-24338928

RESUMO

The design of molecule-based systems combining magnetic, chiroptical and second-order optical nonlinear properties is still very rare. We report an unusually unsymmetric diiron(III) complex 1, in which three bulky chiral carboranylpyridinealkoxide ligands (oCBhmp(-)) bridge both metal ions and the complex shows the above-mentioned properties. The introduction of o-carborane into the 2-(hydroxymethyl)pyridine (hmpH) architecture significantly alters the coordination of the simple or aryl-substituted 2-hmpH. The unusual architecture observed in 1 seems to be triggered by the poor nucleophilicity of our alkoxide ligand (oCBhmp(-)). A very rare case of spontaneous resolution takes place on precipitation or exposure to solvent vapor for the bulk compound, as confirmed by a combination of single-crystal and powder X-ray diffraction, second-harmonic generation, and circular dichroism. The corresponding enantiopure complexes (+)1 and (-)1 have also been synthesized and fully characterized. This research provides a new building block with unique geometry and electronics to construct coordination complexes with multifunctional properties.

6.
Chem Asian J ; 8(12): 3071-8, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24027238

RESUMO

The reactions of 1,3,8,10-tetrakis(4'-fluorophenyl)-4,5,6,7-tetrathiocino[1,2-b:3,4-b']diimidazolyl-2,9-dithione (4) and molecular diiodine afforded spoke adducts with stoichiometries 4·I2 and 4·3I2 , isolated in the compound 4·3I2·xCH2Cl2·(1-x)I2 (x=0.70), and characterized by single-crystal XRD and FT-Raman spectroscopy. The nature of the reaction products was investigated under the prism of theoretical calculations carried out at the DFT level. The structural data, FT-Raman spectroscopy, and quantum mechanical calculations agree in indicating that the introduction of fluorophenyl substituents results in a lowering of the Lewis basicity of this class of bis(thiocarbonyl) donors compared with alkyl-substituted tetrathiocino donors and fluorine allows for extended interactions that are responsible for solid-state crystal packing.

7.
Acta Crystallogr C ; 68(Pt 10): o421-6, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23007547

RESUMO

The isostructural crystals of 4-cyano-N-(4-methoxyphenyl)benzenesulfonamide, C(14)H(12)N(2)O(3)S, (I), N-(4-methoxyphenyl)-4-(trifluoromethyl)benzenesulfonamide, C(14)H(12)F(3)NO(3)S, (II), 4-iodo-N-(4-methoxyphenyl)benzenesulfonamide, C(13)H(12)INO(3)S, (III), 4-bromo-N-(4-methoxyphenyl)benzenesulfonamide, C(13)H(12)BrNO(3)S, (IV), 4-chloro-N-(4-methoxyphenyl)benzenesulfonamide, C(13)H(12)ClNO(3)S, (V), 4-fluoro-N-(4-methoxyphenyl)benzenesulfonamide, C(13)H(12)FNO(3)S, (VI), N-(4-chlorophenyl)-4-methoxybenzenesulfonamide, C(13)H(12)ClNO(3)S, (VII), and 4-cyano-N-phenylbenzenesulfonamide, C(13)H(10)N(2)O(2)S, (VIII), contain infinite chains composed of N-H···O(sulfonyl) hydrogen-bonded molecules. The crystal structures of (I)-(VIII) have been compared using the XPac software and quantitative descriptors of isostructurality were generated [Gelbrich, Threlfall & Hursthouse (2012). CrystEngComm, 14, 5454-5464]. Certain isostructural relationships in this series involve molecules with substantially different spatial demands, e.g. (VI) and (VIII) are related by the simultaneous interchange of F→CN on the benzenesulfonamide ring and OMe→H on the N-phenyl ring, which indicates that the geometry of the three-dimensional crystal-packing mode of (I)-(VIII) is unusually adaptable to different molecular shapes.

8.
Dalton Trans ; 41(22): 6611-3, 2012 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-22543502

RESUMO

The first example of a metal complex containing a tribromide anion is presented and characterised by X-ray diffraction. Hybrid DFT calculations were used to investigate the nature of the bond in coordinating trihalides and the differences with the corresponding mono-halide complexes.

9.
Dalton Trans ; 41(23): 7005-12, 2012 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-22546993

RESUMO

The synthesis of two new tripodal complexes [Ru(L3)](PF(6))(2) and [Ru(L4)](PF(6))(2), encapsulating a ruthenium(II) cation, has been successfully achieved and the products fully characterized, including by X-ray structural determination. The smaller cavity, built around a tris(2-aminoethyl)amido scaffold demonstrated only moderate and predictable interactions with a range of anions and no significant spectroscopic change with nitrate, chloride and bromide, although dihydrogen phosphate did result in an almost stoichiometric precipitation. The expansion of the cavity to include the more rigid 1,3,5-benzenetricarbonylamide group creates a larger cavity, which shows a decrease in the emission on the introduction of chloride, bromide, hydrogen sulfate and nitrate salts, with the (1)H NMR titrations giving a surprisingly high binding affinity for nitrate over the smaller and simpler halides.


Assuntos
Éteres de Coroa/química , Nitratos/química , Compostos Organometálicos/química , Rutênio/química , Espectroscopia de Ressonância Magnética , Especificidade por Substrato
10.
Chem Commun (Camb) ; 48(34): 4061-3, 2012 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-22437480

RESUMO

Instead of highly symmetrical T-symmetry cages common in self-assembly, the p-NMe(2)-substituted triphosphine CH(3)C{CH(2)P(4-C(6)H(4)NMe(2))(3) gives open, polar C(3) symmetry cages [Ag(6)(triphos)(4)X(3)](3+) which lack one of the expected face-capping anions; despite its subtlety this difference occurs selectively in solution and two examples have been crystallographically characterised.

11.
Dalton Trans ; 41(15): 4396-403, 2012 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-22344458

RESUMO

The synthesis and characterization of a series of cyclo-alkylammonium pentaborate salts {[cyclo-C(n)H(2n-1)NR(3)][B(5)O(6)(OH)(4)] (R = H, n = 3, 5-7 (1-4); R = Me, n = 6 (5))} are reported. Compounds 1, 2 and 5 have been further characterized by single-crystal XRD studies. Attempted recrystallization of 3 and 4 yielded small crops of the unexpected heptaborate salts, [cyclo-C(6)H(11)NH(3)](2)[B(7)O(9)(OH)(5)]·3H(2)O·B(OH)(3) (6) and [cyclo-C(7)H(13)NH(3)](2)[B(7)O(9)(OH)(5)]·2H(2)O·2B(OH)(3) (7) which were also characterized crystallographically. All compounds show extensive supramolecular H-bonded anionic lattices templated by the cations. H-bond interactions are described in detail. TGA-DSC analysis of the pentaborates 1-5 showed that they thermally decomposed in air at 800 °C to 2.5B(2)O(3), in a 2 step process involving dehydration (<250 °C) and oxidative decomposition (250-600 °C). BET analysis of materials derived from the pentaborates had internal porosities of <1 m(2) g(-1).

12.
Dalton Trans ; 41(7): 2048-59, 2012 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-22180858

RESUMO

A range of fluoride-encapsulated octasilsesquioxane cage compounds have been prepared using the TBAF route. Our studies suggest that whilst it is relatively straightforward to prepare fluoride-encapsulated octasilsesquioxane cage compounds with adjacent sp(2) carbons, leading to a range of aryl and vinyl substituted compounds, the corresponding sp(3) carbon derivatives are more capricious, requiring an electron withdrawing group that can stabilize the cage whilst not acting as a leaving group. Analysis by X-ray crystallography and solution (19)F/(29)Si NMR spectroscopy of R(8)T(8)@F(-) reveal very similar environments for the encapsulated fluoride octasilsesquioxane cages. Migration of a fluoride ion from inside the cage to outside the cage without breaking the T(8) framework and the possibility of encapsulating other anions within silsesquioxane cages have been also investigated.

13.
J Phys Chem A ; 115(42): 11775-87, 2011 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-21902277

RESUMO

The structure of 2-(2-pyridylimino)-2H-1,2,4-thiadiazolo[2,3-a]pyridine (NSN) indicates that the molecule has a planar geometry with a linear N···S···N linkage, creating a tetracyclic structure of the formal C(2v) symmetry. To clarify the nature of the NSN σ(3c-4e) bonding, together with the related NSeN and NTeN, the dynamic and static behaviors are investigated by applying atoms-in-molecules (AIM) dual functional analysis to both the fully optimized and perturbed structures. The structures were optimized computationally, retaining C(2v) symmetry. All bond critical points are detected as expected and exhibited on both sides of the N···Z···N moiety which supports the formation of NZN σ(3c-4e). It is confirmed that N···S···N is of the covalent nature close to Me(2)S(+)-∗-Cl or Me(2)Se(+)-∗-Br, whereas N···Se···N and N···Te···N have the (regular) CS nature close to the CT adducts of Me(2)S(-∗-Cl)(2) (TBP) and Me(2)Se-∗-Br(2) (MC), respectively. An experimental high-resolution charge density determination has been performed on NSN, which thoroughly supports the theoretical results. Very similar results are obtained in the analogous pyrimidyl derivatives for N···S···N, N···Se···N, and N···Te···N. AIM dual functional analysis, as validated by experimental high-resolution charge densities, is thus confirmed to be an excellent method to elucidate the nature of these interactions.

14.
Chem Commun (Camb) ; 47(27): 7725-7, 2011 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-21655554

RESUMO

Valuable amino benzo[g,h,i]perylenes have been obtained through a one pot electrophilic aromatic substitution--Scholl reaction sequence. Novel molecular architectures combining 3D-o-carborane and planar amino benzo[g,h,i]perylene units are described. Photophysical properties of amino benzo[g,h,i]perylene and the carborane-appended derivatives are discussed.

15.
Dalton Trans ; 40(12): 2983-94, 2011 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-21327226

RESUMO

The structure, synthesis and magnetic properties of three new complex cobalt hydroxyl oxalates are presented, showing a modification of the 2-D double layer hydroxide structure. Co(12)(OH)(18)(ox)(3)(pip) [ox = oxalate, C(2)O(4)(2-); pip = piperazine, C(4)N(2)H(10)] (1), is essentially built from brucite-like layers with a one ninth depletion of the octahedral sites and a preservation of a trigonal crystallographic symmetry. ACo(28)(OH)(43)(ox)(6)Br(2)(H(2)O)(2) [A = Na (2), K (3)] are similarly composed of a brucite-like layer with three nineteenths depletion of octahedral sites, again preserving a trigonal symmetry. Both 2 and 3 show a small degree of structural disorder within the framework. All of these compounds have alternating layers of a mineral-like metal hydroxide structure and a metal oxalate coordination network, with the depletion in the hydroxyl layers being templated by the coordination network. Magnetic studies of 1 reveal a metamagnetic character, with the onset of an antiferromagnetic phase below T(c) = 23.5 K (H = 0 G), and a first order antiferromagnet to metamagnet transition at H(c) = 500-1000 G (T = 20-6 K). Compound 3 shows a more conventional ferrimagnetic ordering below 33(±1) K with a small coercive field of 107(±5) G at 10 K.

16.
Beilstein J Org Chem ; 6: 1002-14, 2010 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-21085502

RESUMO

We present a series of compounds by exploiting the unusual 1,4-aryl shift observed for electron-rich 1,3-dithiole-2-thione and tetrathiafulvalene (TTF) derivatives in the presence of perchloric acid. The mechanistic features of this rearrangement are discussed since this synthetic strategy provides an alternative route for the synthesis and functionalisation of sulfur rich compounds including redox active compounds of TTFs, and a Ni dithiolene.

17.
Inorg Chem ; 49(17): 7853-60, 2010 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-20799737

RESUMO

The X-ray structural and NMR characterization of a bis-guanine derivative of a cisplatin analogue designed to reduce the rate of the Pt-N7 rotation of the coordinated guanine nucleobases by more than 1-million-fold is reported. The [Pt{(+/-)-Me(2)dab}(9-EtG)(2)](NO(3))(2) (Me(2)dab = N,N'-dimethyl-2,3-diaminobutane, 9-EtG = 9-ethyl-guanine) complex crystallizes in the P2(1)/n space group, and the crystal contains a racemic mixture of complex molecules. The data were collected at 120 +/- 2 K, and the crystal and molecular structure (comprising one disordered nitrate) were resolved and refined to conventional agreement factors of R1 = 0.0270 and wR2 = 0.0565. The guanine ligands assume the less common head-to-head (HH) orientation, disclosing full details of the intramolecular relationships between cis guanines and between guanine and cis amine. Moreover, an understanding has been gained of the steric factors determining induction of asymmetry (from carbons to adjacent nitrogen atoms) and puckering of the chelate ring (delta or lambda for R,S,S,R or S,R,R,S configurations at the N,C,C,N chelate-ring atoms, respectively) within the Me(2)dab ligand. The chemical shift separation between H8 signals of the two HT atropisomers and between the two H8 signals of the single HH atropisomer can be explained in terms of canting of the nucleobases relative to the coordination plane and in terms of the different relationships between the H8 proton of one guanine and the shielding zone of the cis guanine. Furthermore, for each configuration of the Me(2)dab ligand (R,S,S,R or S,R,R,S), the NMR data indicate that the handedness of canting is similar for the two guanines in all three (two HT and one HH) conformers (R canting for R,S,S,R and L canting for S,R,R,S configuration).


Assuntos
Antineoplásicos/química , Cisplatino/análogos & derivados , Guanina/análogos & derivados , Nitrogênio/química , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular , Prótons
18.
Inorg Chem ; 49(18): 8545-51, 2010 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-20718486

RESUMO

Six new layered lanthanide molybdate and tungstate phases pillared by either naphthalenedisulfonate (NDS) or fumarate anions have been synthesized hydrothermally and structurally characterized. Five of these materials, [Nd(H(2)O)MoO(4)](2)[2,6-NDS] (1), [Nd(H(2)O)MoO(4)](2)[1,5-NDS] (2), [La(H(2)O)WO(4)](2)[1,5-NDS] (3), [La(H(2)O)WO(4)](2)[2,6-NDS] (4), and [Ce(H(2)O)MoO(4)](2)[fumarate] (6), have a closely related cationic inorganic layer structure which comprises a bilayer of polyhedra leading to the formation of a framework layer containing small, inaccessible pores. These layers are pillared by the organic anions which also bridge between the lanthanide cations within the layers. In the La/WO(4)/2,6-NDS system, a second polymorph, [La(2)(H(2)O)(2)W(2)O(8)][2,6-NDS] (5), is observed. In this compound, the tungstate anions have dimerized, forming W(2)O(8)(4-). This dimer is unique and comprises two square-based pyramidal tungsten centers which are opposed to each other.

19.
Org Biomol Chem ; 8(20): 4653-65, 2010 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-20714669

RESUMO

The extent to which deuterium can act as a protecting group to prevent unwanted 1,5-hydrogen atom transfer to aryl and vinyl radical intermediates was examined in the context of the generation of α-aminoalkyl radicals in a pyrrolidine ring. Intra- and intermolecular radical trapping following hydrogen atom transfer provides an illustration of the use of the primary kinetic isotope effect in directing the outcome of synthetic C-C bond-forming processes.


Assuntos
Deutério/química , Radicais Livres/química , Hidrogênio/química , Ligação de Hidrogênio , Cinética , Modelos Moleculares
20.
Acta Crystallogr C ; 66(Pt 6): o284-8, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20522946

RESUMO

5-Acetyl-2-chloro-8,11-dimethyl-5,6,11,12-tetrahydrodibenzo[b,f]azocine, C(19)H(20)ClNO, (I), crystallizes as a single fully ordered isomer, but 14-acetyl-8,11-dimethyl-7,8,13,14-tetrahydrobenzo[f]naphtho[1,2-b]azocine-14-acetyl-8,9-dimethyl-7,8,13,14-tetrahydrobenzo[f]naphtho[1,2-b]azocine (74/26), C(23)H(23)NO, (II), exhibits threefold whole-molecule disorder involving both configurational and structural isomers. In (I) and in the predominant form of (II), the azocine rings adopt very similar conformations, forming boat-shaped rings having approximate twofold rotational symmetry. There are no direction-specific intermolecular interactions in the crystal structure of (I), but the molecules of (II) are weakly linked into chains by an aromatic pi-pi stacking interaction. The compounds were made under green conditions using an acid-catalysed cyclization process having very high atom utilization.

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