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The crystal structures of two inter-mediates, 4-amino-3,5-di-fluoro-benzo-nitrile, C 7 H 4 F 2 N 2 ( I ), and ethyl 4-amino-3,5-di-fluoro-benzoate, C 9 H 9 F 2 NO 2 ( II ), along with a visible-light-responsive azo-benzene derivative, diethyl 4,4'-(diazene-1,2-di-yl)bis-(3,5-di-fluoro-benzoate), C 18 H 14 F 4 N 2 O 4 ( III ), obtained by four-step synthetic procedure, were studied using single-crystal X-ray diffraction. The mol-ecules of I and II demonstrate the quinoid character of phenyl rings accompanied by the distortion of bond angles related to the presence of fluorine substituents in the 3 and 5 ( ortho ) positions. In the crystals of I and II , the mol-ecules are connected by N-H⋯N, N-H⋯F and N-H⋯O hydrogen bonds, C-H⋯F short contacts, and π-stacking inter-actions. In crystal of III , only stacking inter-actions between the mol-ecules are found., (© Novikov et al. 2024.)

The title compound, systematic name tris-(μ 2 -perfluoro- o -phenyl-ene)(μ 2 -3-phenyl-4 H -chromen-4-one)- triangulo -trimercury, [Hg 3 (C 6 F 4 ) 3 (C 15 H 10 O 2 )], crystallizes in the monoclinic P 2 1 / n space group with one flavone (FLA) and one cyclic trimeric perfluoro- o -phenyl-enemercury (TPPM) mol-ecule per asymmetric unit. The FLA mol-ecule is located on one face of the TPPM acceptor and is linked in an asymmetric coordination of its carbonyl oxygen atom with two Hg centers of the TPPM macrocycle. The angular-shaped complexes pack in zigzag chains where they stack via two alternating TPPM-TPPM and FLA-FLA stacking patterns. The distance between the mean planes of the neighboring TPPM macrocycles in the stack is 3.445 (2) Å, and that between the benzo-γ-pyrone moieties of FLA is 3.328 (2) Å. The neighboring stacks are inter-digitated through the shortened F⋯F, CH⋯F and CH⋯π contacts, forming a dense crystal structure., (© Novikov et al. 2024.)

A Cu II coordination polymer, catena -poly[[[aqua-copper(II)]-bis-(μ-4-amino-benz-o-ato)-κ 2 N : O ;κ 2 O : N ] monohydrate], {[Cu( p ABA) 2 (H 2 O)]·H 2 O} n ( p ABA = p -amino-benzoate, C 7 H 4 NO 2 - ), was synthesized and characterized. It exhibits a one-dimensional chain structure extended into a three-dimensional supra-molecular assembly through hydrogen bonds and π-π inter-actions. While the twinned crystal shows a metrically ortho-rhom-bic lattice and an apparent space group Pbcm , the true symmetry is monoclinic (space group P 2/ c ), with disordered Cu atoms and mixed roles of water mol-ecules (aqua ligand/crystallization water). The luminescence spectrum of the complex shows an emission at 345 nm, cf. 349 nm for p ABAH., (© Gogia et al. 2024.)

1,3-Dimethyl-2,3-dihydrobenzo[ d ]imidazoles, 1H , and 1,1',3,3'-tetramethyl-2,2',3,3'-tetrahydro-2,2'-bibenzo[ d ]imidazoles, 1 2 , are of interest as n-dopants for organic electron-transport materials. Salts of 2-(4-(dimethylamino)phenyl)-4,7-dimethoxy-, 2-cyclohexyl-4,7-dimethoxy-, and 2-(5-(dimethylamino)thiophen-2-yl)benzo[ d ]imidazolium ( 1g-i + , respectively) have been synthesized and reduced with NaBH 4 to 1gH , 1hH , and 1iH , and with Na:Hg to 1g 2 and 1h 2 . Their electrochemistry and reactivity were compared to those derived from 2-(4-(dimethylamino)phenyl)- ( 1b + ) and 2-cyclohexylbenzo[ d ]imidazolium ( 1e + ) salts. E ( 1 + / 1 • ) values for 2-aryl species are less reducing than for 2-alkyl analogues, i.e., the radicals are stabilized more by aryl groups than the cations, while 4,7-dimethoxy substitution leads to more reducing E ( 1 + / 1 • ) values, as well as cathodic shifts in E ( 1 2 •+ / 1 2 ) and E ( 1H •+ / 1H ) values. Both the use of 3,4-dimethoxy and 2-aryl substituents accelerates the reaction of the 1H species with PC 61 BM. Because 2-aryl groups stabilize radicals, 1b 2 and 1g 2 exhibit weaker bonds than 1e 2 and 1h 2 and thus react with 6,13-bis(triisopropylsilylethynyl)pentacene ( VII ) via a "cleavage-first" pathway, while 1e 2 and 1h 2 react only via "electron-transfer-first". 1h 2 exhibits the most cathodic E ( 1 2 •+ / 1 2 ) value of the dimers considered here and, therefore, reacts more rapidly than any of the other dimers with VII via "electron-transfer-first". Crystal structures show rather long central C-C bonds for 1b 2 (1.5899(11) and 1.6194(8) Å) and 1h 2 (1.6299(13) Å)., (Copyright © 2023, Mohapatra et al.)

Substituted acetamides (many of which are chiral) are known to be pharmacologically active. 2-Phenylpropionamide (2PPA) is one of the simplest chiral α-substituted acetamides and thus is of interest as a model compound in the growth and design of pharmaceutical crystals. In this study, the crystal structures of racemic and enantiopure forms of 2PPA were determined for the first time using single crystal X-ray diffraction at 100 K. The relationship between the signs of optical rotation and the absolute configurations is (+)-( S )-2PPA and (-)-( R )-2PPA. Four symmetrically independent molecules with different conformations are observed in crystals of both racemic and enantiopure forms. Remarkably, all forms adopt very similar supramolecular structures, H-bonded corrugated layers, that can be described using a R 2 2 ( 8 ) R 6 4 ( 16 ) graph set. The outer surfaces of these layers are built of nonpolar phenyl groups, and their inner structures are composed of H-bonded amide groups. The presence of these layers determines the thin plate shape of 2PPA crystals. Spectroscopically, the racemic and enantiopure forms substantially differ only in the low-frequency Raman region. X-ray diffraction data suggest that the racemic form of 2PPA is a partial solid solution made possible by statistical occupancy of molecular positions by ( R )- and ( S )-enantiomers.

A new pseudopolymorph of berberine, 9,10-dimeth-oxy-5,6-di-hydro-2 H -7λ 5 -[1,3]dioxolo[4,5- g ]iso-quinolino-[3,2- a ]isoquinolin-7-ylium chloride methanol monosolvate, C 20 H 18 NO 4 + ·Cl - ·CH 3 OH, was obtained during co-crystallization of berberine chloride with malonic acid from methanol. The berberine cations form dimers, which are further packed in stacks. The title structure was compared with other reported solvates of berberine chloride: its dihydrate, tetra-hydrate, and ethanol solvate hemihydrate. Hirshfeld analysis was performed to show the inter-molecular inter-actions in the crystal structure of the title compound, and its fingerprint plots were compared with those of the already studied solvates., (© Kornilova et al. 2022.)

Copper(II) complexes with 1,1,1-trifluoro-4-(4-methoxyphenyl)butan-2,4-dione (H L1 ) were synthesized and characterized by elemental analysis, FT-IR spectroscopy, and single crystal X-ray diffraction. The biological properties of H L1 and cis -[Cu( L1 ) 2 (DMSO)] ( 3 ) were examined against Gram-positive and Gram-negative bacteria and opportunistic unicellular fungi. The cytotoxicity was estimated towards the HeLa and Vero cell lines. Complex 3 demonstrated antibacterial activity towards S. aureus comparable to that of streptomycin, lower antifungal activity than the ligand H L1 and moderate cytotoxicity. The bioactivity was compared with the activity of compounds of similar structures. The effect of changing the position of the methoxy group at the aromatic ring in the ligand moiety of the complexes on their antimicrobial and cytotoxic activity was explored. We propose that complex 3 has lower bioavailability and reduced bioactivity than expected due to strong intermolecular contacts. In addition, molecular docking studies provided theoretical information on the interactions of tested compounds with ribonucleotide reductase subunit R2, as well as the chaperones Hsp70 and Hsp90, which are important biomolecular targets for antitumor and antimicrobial drug search and design. The obtained results revealed that the complexes displayed enhanced affinity over organic ligands. Taken together, the copper(II) complexes with the trifluoromethyl methoxyphenyl-substituted β-diketones could be considered as promising anticancer agents with antibacterial properties.

[RuCp*(1,3,5-R 3 C 6 H 3 )] 2 {Cp* = η 5 -pentamethylcyclopentadienyl, R = Me, Et} have previously been found to be moderately air stable, yet highly reducing, with estimated D + /0.5D 2 (where D 2 and D + represent the dimer and the corresponding monomeric cation, respectively) redox potentials of ca. -2.0 V vs. FeCp 2 +/0 . These properties have led to their use as n-dopants for organic semiconductors. Use of arenes substituted with π-electron donors is anticipated to lead to even more strongly reducing dimers. [RuCp*(1-(Me 2 N)-3,5-Me 2 C 6 H 3 )] + PF 6 - and [RuCp*(1,4-(Me 2 N) 2 C 6 H 4 )] + PF 6 - have been synthesized and electrochemically and crystallographically characterized; both exhibit D + /D potentials slightly more cathodic than [RuCp*(1,3,5-R 3 C 6 H 3 )] + . Reduction of [RuCp*(1,4-(Me 2 N) 2 C 6 H 4 )] + PF 6 - using silica-supported sodium-potassium alloy leads to a mixture of isomers of [RuCp*(1,4-(Me 2 N) 2 C 6 H 4 )] 2 , two of which have been crystallographically characterized. One of these isomers has a similar molecular structure to [RuCp*(1,3,5-Et 3 C 6 H 3 )] 2 ; the central C-C bond is exo , exo , i.e. , on the opposite face of both six-membered rings from the metals. A D + /0.5D 2 potential of -2.4 V is estimated for this exo , exo dimer, more reducing than that of [RuCp*(1,3,5-R 3 C 6 H 3 )] 2 (-2.0 V). This isomer reacts much more rapidly with both air and electron acceptors than [RuCp*(1,3,5-R 3 C 6 H 3 )] 2 due to a much more cathodic D 2 ˙ + /D 2 potential. The other isomer to be crystallographically characterized, along with a third isomer, are both dimerized in an exo , endo fashion, representing the first examples of such dimers. Density functional theory calculations and reactivity studies indicate that the central bonds of these two isomers are weaker than those of the exo , exo isomer, or of [RuCp*(1,3,5-R 3 C 6 H 3 )] 2 , leading to estimated D + /0.5D 2 potentials of -2.5 and -2.6 V vs. FeCp 2 +/0 . At the same time the D 2 ˙ + /D 2 potentials for the exo , endo dimers are anodically shifted relative to those of [RuCp*(1,3,5-R 3 C 6 H 3 )] 2 , resulting in much greater air stability than for the exo , exo isomer.

The geometry of the title mol-ecule [systematic name: 2-(2-nitro-phen-yl)-4 H -chromen-4-one], C 15 H 9 NO 4 , is determined by two dihedral angles formed by the mean plane of phenyl ring with the mean planes of chromone moiety and nitro group, being 50.73 (5) and 30.89 (7)°, respectively. The crystal packing is determined by π-π inter-actions and C-H⋯O contacts. The results of DFT calculations at the B3LYP/6-31G* level of theory provided an explanation of the unusually large dihedral angle between the chromone moiety and the phenyl group. The electrostatic potential map on the mol-ecular surface was calculated in order to determine the potential binding sites to receptors., (© Oskolkov et al. 2020.)

Crystallization from solutions containing 2,2'-[naphthalene-1,8:4,5-bis(dicarboximide)- N,N '-diyl]-bis(ethylammonium) diiodide ((NDIC2)I 2 ) and PbI 2 has been investigated. Eight different materials are obtained, either by variation of crystallization conditions or by subsequent thermal or solvent-induced transformations. Crystal structures have been determined for five materials. [(NDIC2) 2 Pb 5 I 14 (DMF) 2 ]·4DMF (DMF = N,N -dimethylformamide) ( 1 ), [(NDIC2)Pb 4 I 10 ]·4DMF ( 3 ), [(NDIC2)Pb 2 I 6 ]·4NMP (NMP = N -methyl-2-pyrrolidone) ( 4 ), and [(NDIC2)Pb 2 I 6 ]·2H 2 O ( 5 ) form 1-dimensional (1D) chains consisting of PbI 6 (and, in the case of 1 , PbI 5 (DMF)) octahedra, either solely face-sharing or a mixture of face-sharing and vertex-sharing. The structure of [(NDIC 2 ) 3 Pb 5 I 16 ]·6NMP ( 2 ) contains 0D clusters; these consist of three PbI 6 octahedra and two unusually coordinated lead centers that exhibit three relatively short Pb-I bonds, two very long Pb-I contacts, and η 2 -coordination of an aromatic ring of NDIC2 to the lead. Close contacts between iodide ions and the imide rings of NDIC2 in four of the structures suggest that an iodide-to-NDIC2 charge-transfer interaction may be responsible for the observed red coloration of the materials. The optical and electrical properties of 1 have been studied; its onset of absorption is at 2.0 eV, and its conductivity was measured as 5.4 × 10 -5 ± 1.1 × 10 -5 S m -1 .

The title compound DBNB, C 24 H 20 N 2 O 6 , has been crystallized and studied by X-ray diffraction, spectroscopic and computational methods. In the title mol-ecule, which is based on a 1,4-distyryl-2,5-di-meth-oxy-benzene core with p -nitro-substituted terminal benzene rings, the dihedral angle between mean planes of the central fragment and the terminal phenyl ring is 16.46 (6)°. The crystal packing is stabilized by π-π inter-actions. DFT calculations at the B3LYP/6-311 G(d,p) level of theory were used to compare the optimized structures with the experimental data. Energy parameters, including HOMO and LUMO energies, their difference, and vertical excitation and emission energies were obtained., (© Bogdanov et al. 2020.)

The two isomers 2'-(4-nitro-benzo-yloxy)aceto-phenone (systematic name: 2-acetyl-phenyl 4-nitro-benzoate) ( I ) and 2'-(2-nitro-benzo-yloxy)aceto-phenone (systematic name: 2-acetyl-phenyl 2-nitro-benzoate) ( II ), both C 15 H 11 NO 5 , with para and ortho positions of the nitro substituent have been crystallized and studied. It is evident that the variation in the position of the nitro group causes a significant difference in the mol-ecular conformations: the dihedral angle between the aromatic fragments in the mol-ecule of I is 84.80 (4) ° , while that in the mol-ecule of II is 6.12 (7) ° . Diffraction analysis revealed the presence of a small amount of water in the crystal of I . DFT calculations of the mol-ecular energy demonstrate that the ortho substituent causes a higher energy for isomer II , while crystal lattice energy calculations show that the values are almost equal for two isomers., (© Bogdanov et al. 2020.)

The three organic two-photon-absorbing cycloalkanone chromophores 2,4-bis[4-(diethylamino)benzylidene]cyclobutanone, C 26 H 32 N 2 O (I), 2,5-bis[4-(diethylamino)benzylidene]cyclopentanone, C 27 H 34 N 2 O (II), and 2,6-bis[4-(diethylamino)benzylidene]cyclohexanone, C 28 H 36 N 2 O (III), were obtained by a reaction between 4-(diethylamino)benzaldehyde and the corresponding cycloalkanone and were characterized by single-crystal X-ray diffraction studies, as well as density functional theory (DFT) quantum-chemical calculations. Molecules of this series have three main fragments, i.e. central acceptor (A) and two terminal donors (D 1 and D 2 ) and represent examples of the D 1 -π-A-π-D 2 molecular design. All three compounds crystallize with two crystallographically independent molecules in the asymmetric unit (A and B) and are distinguished by the conformations of both the molecular Et 2 N-C 6 H 4 -C=C-C(=O)-C=C-C 6 H 4 -NEt 2 backbone (arcuate or linear) and the terminal diethylamino substituents (syn- or antiperiplanar to the plane of the molecule). The central four- and five-membered rings in I and II are almost planar, and the six-membered ring in III adopts a sofa conformation. In the crystals of I-III, the two independent molecules A and B form hydrogen-bonded [A...B] dimers via intermolecular C-H...O hydrogen bonds. Furthermore, the [A...B] dimers in I are bound by intermolecular C-H...O hydrogen bonds into two-tier puckered layers, whereas in the crystals of II and III, the [A...B] dimers are stacked along the c and a axes, respectively. Taking into account the decreasing steric strain upon expanding the central ring, compound I might be more efficient as a two-photon absorption chromophore than compounds II and III, which corresponds to the results of spectroscopic studies.

The title compound, C 4 H 12 N + ·C 11 H 5 N 4 - , contains one tetra-methyl-ammonium cation and one 1,1,7,7-tetra-cyano-hepta-2,4,6-trienide anion in the asymmetric unit. The anion is in an all- trans conjugated C=C bonds conformation. Two terminal C(CN) 2 di-nitrile moieties are slightly twisted from the polymethine main chain to which they are attached [C(CN) 2 /C 5 dihedral angles = 6.1 (2) and 7.1 (1)°]. The C-C bond distances along the hepta-dienyl chain vary in the narrow range 1.382 (2)-1.394 (2) Å, thus indicating the significant degree of conjugation. In the crystal, the anions are linked into zigzag chains along the [10] direction by C-H⋯N(nitrile) short contacts. The anti-parallel chains stack along the [110] direction with alternating separations between the neighboring anions in stacks of 3.291 and 3.504 Å. The C-H⋯N short contacts and stacking inter-actions combine to link the anions into layers parallel to the (01) plane and separated by columns of tetra-methyl-ammonium cations.

Two compounds, 1,3-diethyl-5-{(2 E ,4 E )-6-[( E )-1,3,3-tri-methyl-indolin-2-yl-idene]hexa-2,4-dien-1-yl-idene}pyrimidine-2,4,6(1 H ,3 H ,5 H )-trione or TMI, C 25 H 29 N 3 O 3 , and 1,3-diethyl-2-sulfanyl-idene-5-[2-(1,3,3-tri-methyl-indolin-2-yl-idene)ethyl-idene]di-hydro-pyrimidine-4,6(1 H ,5 H )-dione or DTB, C 21 H 25 N 3 O 2 S, have been crystallized and studied. These compounds contain the same indole derivative donor group and differ in their acceptor groups (in TMI it contains oxygen in the para position, and in DTB sulfur) and the length of the π-bridge. In both materials, mol-ecules are packed in a herringbone manner with differences in the twist and fold angles. In both structures, the mol-ecules are connected by weak C-H⋯O and/or C-H⋯S bonds.

The synthesis, crystal structure studies and solvatochromic behavior of 2-{(2E,4E)-5-[4-(dimethylamino)phenyl]penta-2,4-dien-1-ylidene}malononitrile, C 16 H 15 N 3 (DCV[3]), and 2-{(2E,4E,6E)-7-[4-(dimethylamino)phenyl]hepta-2,4,6-trien-1-ylidene}malononitrile, C 18 H 17 N 3 (DCV[4]), are reported and discussed in comparison with their homologs having a shorter length of the π-conjugated bridge. The compounds of this series have potential use as nonlinear materials with second-order effects due to their donor-acceptor structures. However, DCV[3] and DCV[4] crystallized in the centrosymmetric space group P2 1 /c which excludes their application as nonlinear optical materials in the crystalline state. They both crystallize with two independent molecules having the same molecular conformation in the asymmetric unit. The series DCV[1]-DCV[4] demonstrated reversed solvatochromic behavior in toluene, chloroform, and acetonitrile.

The Z and E isomers of 3-[4-(dimethylamino)phenyl]-2-(2,4,6-tribromophenyl)acrylonitrile, C 17 H 13 Br 3 N 2 , (1), were obtained simultaneously by a Knoevenagel condensation between 4-(dimethylamino)benzaldehyde and 2-(2,4,6-tribromophenyl)acetonitrile, and were investigated by X-ray diffraction and density functional theory (DFT) quantum-chemical calculations. The (Z)-(1) isomer is monoclinic (space group P2 1 /n, Z' = 1), whereas the (E)-(1) isomer is triclinic (space group P-1, Z' = 2). The two crystallographically-independent molecules of (E)-(1) adopt similar geometries. The corresponding bond lengths and angles in the two isomers of (1) are very similar. The difference in the calculated total energies of isolated molecules of (Z)-(1) and (E)-(1) with DFT-optimized geometries is ∼4.47 kJ mol -1 , with the minimum value corresponding to the Z isomer. The crystal structure of (Z)-(1) reveals strong intermolecular nonvalent Br...N [3.100 (2) and 3.216 (3) Å] interactions which link the molecules into layers parallel to (10-1). In contrast, molecules of (E)-(1) in the crystal are bound to each other by strong nonvalent Br...Br [3.5556 (10) Å] and weak Br...N [3.433 (4) Å] interactions, forming chains propagating along [110]. The crystal packing of (Z)-(1) is denser than that of (E)-(1), implying that the crystal structure realized for (Z)-(1) is more stable than that for (E)-(1).

3-Ethyl-3-phenylpyrrolidin-2-one (EPP) is an experimental anticonvulsant based on the newly proposed α-substituted amide group pharmacophore. These compounds show robust activity in animal models of drug-resistant epilepsy and are thus promising for clinical development. In order to understand pharmaceutically relevant properties of such compounds, we are conducting an extensive investigation of their structures in the solid state. In this article, we report chiral high-performance liquid chromatography (HPLC) separation, determination of absolute configuration of enantiomers, and crystal structures of EPP. Preparative resolution of EPP enantiomers by chiral HPLC was accomplished on the Chiralcel OJ stationary phase in the polar-organic mode. Using a combination of electronic CD spectroscopy and anomalous dispersion of X-rays we established that the first-eluted enantiomer corresponds to (+)-(R)-EPP, while the second-eluted enantiomer corresponds to (-)-(S)-EPP. We also demonstrated that, in the crystalline state, enantiopure and racemic forms of this anticonvulsant have considerable differences in their supramolecular organization and patterns of hydrogen bonding. These stereospecific structural differences can be related to the differences in melting points and, correspondingly, solubility and bioavailability., (© 2017 Wiley Periodicals, Inc.)

Mixed cocrystals derived from electron-rich donor (D) and electron-deficient acceptor (A) molecules showcase electronic, optical, and magnetic properties of interest for a wide range of applications. We explore the structural and electronic properties of a cocrystal synthesized from dithieno[3,2-a:2',3'-c]phenazine (DTPhz) and 7,7,8,8-tetracyanoquinodimethane (TCNQ), which has a mixed-stack packing arrangement of the (π-electronic) face-to-face stacks in a 2:1 D:A stoichiometry. Density functional theory investigations reveal that the primary electronic characteristics of the cocrystal are not determined by electronic interactions along the face-to-face stacks, but rather they are characterized by stronger electronic interactions orthogonal to these stacks that follow the edge-to-edge donor-donor or acceptor-acceptor contacts. These distinctive electronic characteristics portend semiconducting properties that are unusual for semiconducting mixed cocrystals and suggest further potential to design organic semiconductors with orthogonal transport characteristics for different charge carriers.

In the title mol-ecular salt, C 6 H 16 NO + ·Cl - , two of the C-C-N-O groups in the cation adopt a gauche conformation [torsion angles = 62.86 (11) and -54.95 (13)°] and one an anti conformation [-177.82 (10)°. The cation and anion are linked by an O-H⋯Cl hydrogen bond. The extended structure displays C-H⋯Cl and C-H⋯O hydrogen bonds, resulting in layers lying parallel to the (100) plane: further C-H⋯Cl contacts connect the sheets into a three-dimensional network.

Compounds with polarizable π systems that are susceptible to attack with nucleophiles at C-Hal (Hal = Cl, Br) bonds react with Pd(PPh3)4 to yield net oxidative addition. X-ray structures show that the resulting Pd(PPh3)2Hal groups greatly reduce intermolecular π-π interactions. The Pd-functionalized dyes generally exhibit solution-like absorption spectra in films, whereas their Hal analogues exhibit features attributable to aggregation.

The title three-dimensional metal-organic framework (MOF) compound, {(NH4)2[Zn2(C9H3O6)2]·2C5H9NO} n , features an anionic framework constructed from Zn(2+) cations and benzene-1,3,5-tri-carboxyl-ate (BTC) organic anions. Charge balance is achieved by outer sphere ammonium cations formed by degradation of di-n-butyl-amine in the solvothermal synthesis of the compound. Binuclear {Zn2(COO)2} entities act as the framework's secondary building units. Each Zn(II) atom has a tetrahedral coordination environment with an O4 set of donor atoms. The three-dimensional framework adopts a rutile-type topology and channels are filled in an alternating fashion with ordered and disordered 1-methyl-pyrrolidin-2-one solvent mol-ecules and ammonium cations. The latter are held in the channels via four N-H⋯O hydrogen bonds, including three with the benzene-1,3,5-tri-carboxyl-ate ligands of the anionic framework and one with a 1-methyl-pyrrolidin-2-one solvent mol-ecule.

Electron acceptors are important components of π-conjugated materials, but the strong electron-withdrawing properties of the required synthetic intermediates often make them poor substrates in synthetic schemes designed around conventional organometallic cross-coupling. Here, strong benzodiimine-based acceptors, including 5,6-difluoro[2,1,3]benzothiadiazole, 5,6-dicyano[2,1,3]benzothiadiazole, 5,6-dicyanobenzo[d][1,2,3]triazole, 6,7-dicyanoquinoxaline, and 6,7-dinitroquinoxaline, are shown to undergo facile palladium-catalyzed C-H direct arylation with a variety of bromoarenes in moderate to high yields. The electrochemical characteristics of di-2-thienyl derivatives synthesized using this methodology are compared and suggest that, in an electron-transfer sense, 5,6-dicyano[2,1,3]benzothiadiazole is a comparably strong acceptor to benzo[1,2-c:4,5-c']bis[1,2,5]thiadiazole. The synthetic results suggest that high electron-withdrawing ability, which has traditionally limited reaction yields and structural variety in organic electronic materials, may be advantageous when employing C-H activated direct arylation in certain circumstances.

The title compound, [Hg3(C6F4)3]·C6N4, contains one mol-ecule of tetra-cyano-ethyl-ene B per one mol-ecule of mercury macrocycle A, i.e., A•B, and crystallizes in the monoclinic space group C2/c. Macrocycle A and mol-ecule B both occupy special positions on a twofold rotation axis and the inversion centre, respectively. The supra-molecular unit [A•B] is built by the simultaneous coordination of one of the nitrile N atoms of B to the three mercury atoms of the macrocycle A. The Hg⋯N distances range from 2.990 (4) to 3.030 (4) Å and are very close to those observed in the related adducts of the macrocycle A with other nitrile derivatives. The mol-ecule of B is almost perpendicular to the mean plane of the macrocycle A at the dihedral angle of 88.20 (5)°. The donor-acceptor Hg⋯N inter-actions do not affect the C N bond lengths [1.136 (6) and 1.140 (6) Å]. The trans nitrile group of B coordinates to another macrocycle A, forming an infinite mixed-stack [A•B]∞ architecture toward [101]. The remaining N atoms of two nitrile groups of B are not engaged in any donor-acceptor inter-actions. In the crystal, the mixed stacks are held together by inter-molecular C-F⋯C N secondary inter-actions [2.846 (5)-2.925 (5) Å].

Dimers of 2-substituted N,N'-dimethylbenzimidazoline radicals, (2-Y-DMBI)2 (Y=cyclohexyl (Cyc), ferrocenyl (Fc), ruthenocenyl (Rc)), have recently been reported as n-dopants for organic semiconductors. Here their structural and energetic characteristics are reported, along with the mechanisms by which they react with acceptors, A (PCBM, TIPS-pentacene), in solution. X-ray data and DFT calculations both indicate a longer C-C bond for (2-Cyc-DMBI)2 than (2-Fc-DMBI)2 , yet DFT and ESR data show that the latter dissociates more readily due to stabilization of the radical by Fc. Depending on the energetics of dimer (D2 ) dissociation and of D2 -to-A electron transfer, D2 reacts with A to form D(+) and A(-) by either of two mechanisms, differing in whether the first step is endergonic dissociation or endergonic electron transfer. However, the D(+) /0.5 D2 redox potentials-the effective reducing strengths of the dimers-vary little within the series (ca. -1.9 V vs. FeCp2 (+/0) ) (Cp=cyclopentadienyl) due to cancelation of trends in the D(+/0) potential and D2 dissociation energy. The implications of these findings for use of these dimers as n-dopants, and for future dopant design, are discussed., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A fluorene-based donor-acceptor ligand was successfully employed to sensitize visible and near-IR emitting lanthanide centers. The ligand construct is based on a donor-π-acceptor architecture with diphenylamino acting as the donor and a fluorenyl π bridge derivatized with a trifluoroacetonate moiety acting as both a strong acceptor and the classic bidentate scaffold for complexing metals. (1)H NMR analysis in the polar solvents THF and CDCl3 revealed the enolic form of the diketone dominant in solution equilibria at room temperature. This preferred cis-enol form binds strongly to the lanthanide(III) ions (Ln = Eu, Sm, Dy, Tb, Yb, Nd, Er, and Gd) in the presence of phenanthroline affording the resulting ternary tris(diketonates) complexes with 1,10-phenanthroline. Detailed characterization of these complexes was conducted, with particular emphasis on linear and nonlinear photophysical properties. Steady-state and time-resolved emission spectroscopy and overall photoluminescence quantum yield (PLQY) measurements were performed on all the complexes. Sizeable visible and near-IR efficiency for europium (room temperature, visible), samarium (low temperature, visible) and ytterbium, neodymium and erbium (room temperature, near-IR) was displayed, with long luminescent lifetimes for the europium and samarium complexes of 85 and 70 μs, respectively Measurement of the luminescence decay for the Yb complex at 976 nm, Nd complex at 874 nm, and Er complex at 1335 nm yielded mono-exponential decay curves, with lifetimes of ~13 μs, ~1.6 μs, and ~2.5 μs, respectively, inferring that the emission was generated by a single species. In addition, fluorescence anisotropy and two-photon absorption (2PA) spectra (via Z-scan) were obtained for the ligand and europium complex, revealing a maximum 2PA cross section of 340 GM for the latter upon excitation at 760 nm. A quadratic relationship was found by varying laser excitation power vs. luminescence intensity of the europium complex, confirming sensitization via two-photon excitation.

The dimers of some Group 8 metal cyclopentadienyl/arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the X-ray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central CC σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these CC bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2 ]2 , rather similar (-1.97 to -2.15 V vs. FeCp2 (+/0) in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In an attempt to grow 8-hy-droxy-quinoline-acetamino-phen co-crystals from equimolar amounts of conformers in a chloro-form-ethanol solvent mixture at room temperature, the title compound, C9H7NO, was obtained. The mol-ecule is planar, with the hy-droxy H atom forming an intra-molecular O-H⋯N hydrogen bond. In the crystal, mol-ecules form centrosymmetric dimers via two O-H⋯N hydrogen bonds. Thus, the hy-droxy H atoms are involved in bifurcated O-H⋯N hydrogen bonds, leading to the formation of a central planar four-membered N2H2 ring. The dimers are bound by inter-molecular π-π stacking [the shortest C⋯C distance is 3.2997 (17) Å] and C-H⋯π inter-actions into a three-dimensional framework. The crystal grown represents a new monoclinic polymorph in the space group P21/n. The mol-ecular structure of the present monoclinic polymorph is very similar to that of the ortho-rhom-bic polymorph (space group Fdd2) studied previously [Roychowdhury et al. (1978 ▶). Acta Cryst. B34, 1047-1048; Banerjee & Saha (1986 ▶). Acta Cryst. C42, 1408-1411]. The structures of the two polymorphs are distinguished by the different geometries of the hydrogen-bonded dimers, which in the crystal of the ortho-rhom-bic polymorph possess twofold axis symmetry, with the central N2H2 ring adopting a butterfly conformation.

Crystal structures of racemic and homochiral forms of 2-phenylbutyramide ( 1 ) and 3-methyl-3-phenylpyrrolidine-2,5-dione ( 2 ) were investigated in detail by a single crystal X-ray diffraction study. Absolute configurations of the homochiral forms of 1 and 2 , obtained by chromatographic separation of racemates, were determined. It was revealed that racemate and homochiral forms of 1 are very similar in terms of supramolecular organization (H-bonded ribbons) in crystal, infrared (IR) spectral characteristics, and melting points. The presence of two different molecular conformations in homochiral forms of 1 allowed mimicking of crystal packing of the H-bonded ribbons in racemate 1 . Two polymorph modifications (monoclinic and orthorhombic) comprising very similar H-bonded zigzag -like chains were found for the homochiral forms of compound 2 that were significantly different in terms of crystal structure, IR spectra, and melting points from the racemic form of 2 . Unlike compound 1 , homochiral forms of compound 2 have a higher density than the corresponding racemate which contradicts the Wallach rule and indicates that, in this case, homochiral forms are more stable than racemate forms.

Metal-organic frameworks (MOFs) can provide a matrix for the assembly of organic chromophores into well-defined geometries, allowing for tuning of the material properties and study of structure-property relationships. Here, we report on the effect of the coordinated metal ion on the luminescence properties of eight isostructural MOFs having the formula M(1)2M(2)L3(DMF)2 (M(1) = M(2) = Zn (1), Cd (2), Mn (3), Co (4); M(1) = Zn, M(2) = Cd (5), Mn (6), Co (7); M(1) = Co, M(2) = Mn (8); L = trans-4,4'-stilbene dicarboxylate), synthesized by reaction of the appropriate metal nitrate or mixtures of metal nitrates with LH2 in DMF. The crystal structures of 2, 3 and 5-8 were determined by X-ray diffraction to be composed of trinuclear metal clusters linked by stilbene dicarboxylate linkers in a paddlewheel geometry, extending to form a 2-D layered structure. In the mixed-metal cases, the larger metal ion was found to occupy the octahedral site in the cluster while the smaller ion occupies the tetrahedral positions, suggesting a selective, ligand-directed assembly process for the mixed-metal species. Variable temperature magnetic measurements for paramagnetic MOFs 3 and 6-8 were consistent with the site occupancies determined crystallographically, and indicated weak intra-cluster antiferromagnetic coupling for 3 and 8. Comparison between the crystal structures of 2, 3 and 5-8 and those reported for 1 and 4 in the literature reveal close resemblances between linker environments, with important intermolecular stilbene-stilbene geometries that are comparable in all cases. Interestingly, pale-colored 1-3 and 5-7 display very similar emission profiles upon excitation at λ(ex) = 350 nm, whereas dark-colored 4 and 8 do not exhibit detectable emission spectra. The bright, well-resolved luminescence of 1, 2 and 5 is ascribed to rigidification of the linker upon coordination to the d(10) metal ions, whereas the weaker emission observed for 3, 6 and 7 is presumably a result of quenching due to close proximity of the linker to one or more paramagnetic ions. Time-resolved measurements for 1, 2, 5 and 6 reveal biexponential emission decays, where the lifetime of the longer-lived state corresponds to observed variations in the nearest-neighbor cofacial stilbene-stilbene distances in their crystal structures. For 3, a monoexponential decay with shorter lifetime was determined, indicating significant paramagnetic quenching of its emissive state.

Arylation in the 4- and 7-positions of 2,1,3-benzothiadiazole (BT) and its monofluoro- (MFBT) and difluoro- (DFBT) derivatives by (hetero)aryl bromides using Pd-catalyzed C–H activation has been investigated. MFBT and DFBT can be diarylated in moderate to high yields (up to 96% for DFBT) by a variety of aryl bromides. DFBT can be sequentially arylated using two different aryl bromides to give differentially substituted DFBT derivatives. The moderate to high yields of doubly arylated MFBT and DFBT and the ability to obtain differentially substituted products can be applied to a variety of organic photonic and electronic materials.

The mol-ecule of the title compound, C15H18N4, adopts a trans conformation with respect to the diazo N=N bond. The dihedral angle between the benzene and pyridine rings in the mol-ecule is 8.03 (5)°. In the crystal, a weak C-H⋯π inter-action arranges the mol-ecules into a corrugated ribbon, with an anti-parallel orientation of neighboring mol-ecules propagating in the [100] direction.

In the title co-crystal, 2C6H5NO·C4H4O4, two crystallographically different hydrogen-bonded trimers are formed, one in which the components occupy general positions, and one generated by an inversion centre. This results in the uncommon situation of Z = 3 for a triclinic crystal. In the formula units, mol-ecules are linked by O-H⋯N hydrogen bonds.

In the title salt, C5H8N3 (+)·C3H3O4 (-), the 3,4-di-amino-pyridinium cation is almost planar, with an r.m.s. deviation of 0.02 Å. The conformation of the hydrogen malonate anion is stabilized by an intra-molecular O-H⋯O hydrogen bond, which generates an S(6) ring. In the crystal, N-H⋯O hydrogen bonds link cations and anions into layers parallel to the ab plane.

The target complexes, bis{(E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-oxopiperidinium} butanedioate, 2C27H36N3O(+)·C4H4O4(2-), (II), and bis{(E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-oxopiperidinium} decanedioate, 2C27H36N3O(+)·C10H16O4(2-), (III), were obtained by solvent-mediated crystallization of the active pharmaceutical ingredient (API) (E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-piperidone and pharmaceutically acceptable dicarboxylic (succinic and sebacic) acids from ethanol solution. They have been characterized by melting point, IR spectroscopy and single-crystal X-ray diffraction. For the sake of comparison, the structure of the starting API, (E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-piperidone methanol monosolvate, C27H35N3O·CH4O, (I), has also been studied. Compounds (II) and (III) represent salts containing H-shaped centrosymmetric hydrogen-bonded synthons, which are built from two parallel piperidinium cations and a bridging dicarboxylate dianion. In both (II) and (III), the dicarboxylate dianion resides on an inversion centre. The two cations and dianion within the H-shaped synthon are linked by two strong intermolecular N(+)-H···(-)OOC hydrogen bonds. The crystal structure of (II) includes two crystallographically independent formula units, A and B. The cation geometries of units A and B are different. The main N-C6H4-C=C-C(=O)-C=C-C6H4-N backbone of cation A has a C-shaped conformation, while that of cation B adopts an S-shaped conformation. The same main backbone of the cation in (III) is practically planar. In the crystal structures of both (II) and (III), intermolecular N(+)-H···O=C hydrogen bonds between different H-shaped synthons further consolidate the crystal packing, forming columns in the [100] and [101] directions, respectively. Salts (II) and (III) possess increased aqueous solubility compared with the original API and thus enhance the bioavailability of the API.

In the title compound, C(4)H(6)N(4)·C(3)H(6)O, the pyrimidine-2,4-diamine mol-ecule is nearly planar (r.m.s. deviation = 0.005 Å), with the endocyclic angles covering the range 114.36 (10)-126.31 (10)°. In the crystal, N-H⋯N and N-H⋯O hydrogen bonds link the mol-ecules into ribbons along [101], and weak C-H⋯π inter-actions consolidate further the crystal packing.

In the title mol-ecule, C6H8N2, the endocyclic angles are in the range 118.43 (9)-122.65 (10)°. The mol-ecular skeleton is planar (r.m.s. deviation = 0.007 Å). One of the two amino H atoms is involved in an N-H⋯N hydrogen bond, forming an inversion dimer, while the other amino H atom participates in N-H⋯π inter-actions between the dimers, forming layers parallel to (100).

In the title mol-ecule, C5H7N3, intra-cyclic angles cover the range 117.15 (10)-124.03 (11)°. The N atoms of the amino groups have trigonal-pyramidal configurations deviating slightly from the pyridine plane by 0.106 (2) and -0.042 (2) Å. In the crystal, the pyridine N atom serves as an acceptor of an N-H⋯N hydrogen bond which links two mol-ecules into a centrosymmetric dimer. Inter-molecular N-H⋯N hydrogen bonds between the amino groups further consolidate the crystal packing, forming a three-dimensional network.

Several 19-electron sandwich compounds are known to exist as "2×18-electron" dimers. Recently it has been shown that, despite their air stability in the solid state, some of these dimers act as powerful reductants when co-deposited from either the gas phase or from solution and that this behavior can be useful in n-doping materials for organic electronics, including compounds with moderate electron affinities, such as 6,13-bis[tri(isopropyl)silylethynyl]pentacene (3). This paper addresses the mechanisms by which the dimers of 1,2,3,4,5-pentamethylrhodocene (1 b(2)), (pentamethylcyclopentadienyl)(1,3,5-trialkylbenzene)ruthenium (alkyl=Me, 2 a(2); alkyl=Et, 2 b(2)), and (pentamethylcyclopentadienyl)(benzene)iron (2 c(2)) react with 3 in solution. Vis/NIR and NMR spectroscopy, and X-ray crystallography indicate that the products of these solution reactions are 3(·-) salts of the monomeric sandwich cations. Vis/NIR kinetic studies for the Group 8 dimers are consistent with a mechanism whereby an endergonic electron transfer from the dimer to 3 is followed by rapid cleavage of the dimer cation. NMR crossover experiments with partially deuterated derivatives suggest that the C-C bond in the 1 b(2) dimer is much more readily broken than that in 2 a(2); consistent with this observation, Vis/NIR kinetic measurements suggest that the solution reduction of 3 by 1 b(2) can occur by both the mechanism established for the Group 8 species and by a mechanism in which an endergonic dissociation of the dimer is followed by rapid electron transfer from monomeric 1 b to 3., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

2,6-Diacyl derivatives of naphthalene-1,8:4,5-bis(dicarboximide)s have been synthesized via Stille coupling reactions of the corresponding 2,6-distannyl derivative with acyl halides. Reaction of these diketones with hydrazine gave phthalazino[6,7,8,1-lmna]pyridazino[5,4,3-gh][3,8]phenanthroline-5,11(4H,10H)-dione fused-ring derivatives. The products were characterized by UV-vis absorption spectroscopy and electrochemistry, modeled using density functional theory calculations, and, in some cases, studied and compared using single-crystal X-ray diffraction.

The two-photon absorption (2PA) spectrum of an organic single crystal is reported. The crystal is grown by self-nucleation of a subsaturated hot solution of acetonitrile, and is composed of an asymmetrical donor-π-acceptor cyanine-like dye molecule. To our knowledge, this is the first report of the 2PA spectrum of single crystals made from a cyanine-like dye. The linear and nonlinear properties of the single crystalline material are investigated and compared with the molecular properties of a toluene solution of its monomeric form. The maximum polarization-dependent 2PA coefficient of the single crystal is 52 ± 9 cm/GW, which is more than twice as large as that for the inorganic semiconductor CdTe with a similar absorption edge. The optical properties, linear and nonlinear, are strongly dependent upon incident polarization due to anisotropic molecular packing. X-ray diffraction analysis shows π-stacking dimers formation in the crystal, similar to H-aggregates. Quantum chemical calculations demonstrate that this dimerization leads to the splitting of the energy bands and the appearance of new red-shifted 2PA bands when compared to the solution of monomers. This trend is opposite to the blue shift in the linear absorption spectra upon H-aggregation.

The synthesis and the antitumor activity and fluorescent properties screening of novel bisphosphonate conjugates with cytotoxic 3,5-bis((hetero)arylidene)-4-piperidone residues were performed. The facile and rapid synthetic route was based on the aza-Michael addition of NH-3,5-bis((hetero)arylidene)-4-piperidones to tetraethyl ethylidenebisphosphonate. The synthesized compounds displayed high inhibitory properties towards Caov3, A549, PC3, and KB 3-1 human carcinoma cell lines. Among those, compounds bearing 4-cyano-phenyl and 3-pyridinyl substituents were revealed as the most active drug candidates with IC(50) values in the range of 0.5-2.5 µM. Methylenebisphosphonate with 4-Me(2) N-C(6) H(4) groups in the piperidone framework possessing fluorescence properties may be of interest for visualization of BPs skeletal distribution and cellular uptake in bones and other tissues., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The structures of tricarbonyl(formylcyclopentadienyl)manganese(I), [Mn(C(6)H(5)O)(CO)(3)], (I), and tricarbonyl(formylcyclopentadienyl)rhenium(I), [Re(C(6)H(5)O)(CO)(3)], (II), were determined at 100 K. Compounds (I) and (II) both possess a carbonyl group in a trans position relative to the substituted C atom of the cyclopentadienyl ring, while the other two carbonyl groups are in almost eclipsed positions relative to their attached C atoms. Analysis of the intermolecular contacts reveals that the molecules in both compounds form stacks due to short attractive π(CO)...π(CO) and π(CO)...π interactions, along the crystallographic c axis for (I) and along the [201] direction for (II). Symmetry-related stacks are bound to each other by weak intermolecular C-H...O hydrogen bonds, leading to the formation of the three-dimensional network.

2-Stannyl and 2,6-distannyl naphthalene diimides (NDIs) can be synthesized through the palladium-catalyzed reaction of the appropriate bromo derivatives with hexabutylditin. The utility of these precursors in palladium catalyzed cross-coupling reactions is demonstrated by the synthesis of bi- and ter-NDI derivatives, UV-vis, cyclic voltammetry, and n-channel organic field-effect transistor data for which are compared to those of the monomeric parent NDI., (© 2012 American Chemical Society)

A novel metal-organic replica of α-PbO(2) exhibits high capacity for capture of nerve agent surrogate.

In order to give further insight on the influence of the aromatic ring nature and the presence of the phosphorus substituent at the piperidone nitrogen atom of E,E-3,5-bis((hetero)arylidene)piperid-4-ones on their antitumor properties, a series of phosphorus substituted E,E-3,5-bis(pyridinylmethylene)piperid-4-ones bearing either 3-pyridine or 4-pyridine rings was obtained. Novel NH-3,5-bis(pyridinylmethylene)piperid-4-ones 1a,b were converted into the corresponding N-phosphorylated derivatives 3a-c, 4a-c differing in the substitution at the phosphorus atom (amidophosphates and amidophosphonates), via direct phosphorylation while N-(ω-phosphorylalkyl)-substituted compounds 8a-c were obtained via aldol-crotonic condensation of preformed N-phosphorylalkyl substituted piperidones with the corresponding pyridinecarboxaldehyde. The cytotoxicity screen has revealed that phosphorylated compounds based on E,E-3,5-bis(4-pyridinylmethylene)piperid-4-one framework displayed higher inhibitory properties toward Caov3, A549, KB 3-1 and KB 8-5 human carcinoma cell lines comparing with their analogues with 3-pyridine rings. Introduction of the phosphorus moiety substantially increased the antitumor properties in the case of E,E-3,5-bis(3-pyridinylmethylene)piperid-4-ones derivatives but this influence less pronounced for more active analogues bearing 4-pyridinyl rings. Most of the compounds tested are potent against multi-drug resistant cell line KB 8-5 affording some guidelines for the search of perspective drug-candidates among phosphorus substituted E,E-3,5-bis((hetero)arylidene)piperid-4-ones., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

A one-pot preparation of the 2,2'-dibromo-1,1'-bisheteroarenes 3a-d from bromo-heteroarenes utilizing the sequence of the base-catalyzed halogen dance (BCHD) reaction and CuCl(2)-promoted oxidative coupling of the in situ formed alpha-lithio-beta-halo-heteroarenes 2a-d provides a convenient access to precursors for the preparation of tricyclic heteroaromatic cores. The structures of 3a,b,d, 6, and 9 were confirmed by single-crystal X-ray analysis, and dibromides 3a and 3b were used for the preparation of dithieno-[2,3-b:3',2'-d]-pyrrole 10a and its selenophene analogue 10b, respectively.

Several N-alkyl and N,N-dialkylaminomethanesulfonic acids were synthesized (as zwitterions and/or sodium salts) to be tested for utility as biological buffers at lower pH levels than existing Good buffer compounds (aminoalkanesulfonates with a minimum of two carbons between amine and sulfonic acid groups as originally described by Norman Good, and in common use as biological buffers). Our hypothesis was that a shorter carbon chain (one carbon) between the amino and sulfonic acid groups should lower the ammonium ion pK(a) values. The alkylaminomethanesulfonate compounds were synthesized in aqueous solution by reaction of primary or secondary amines with formaldehyde/sodium hydrogensulfite addition compound. The pK(a) values of the ammonium ions of this series of compounds (compared to existing Good buffers) was found to correlate well with the length of the carbon chain between the amino and sulfonate moeties, with a significant decrease in amine basicity in the aminomethanesulfonate compounds (pK(a) decrease of 2 units or more compared to existing Good buffers). An exception was found for the 2-hydroxypiperazine series which shows only a small pK(a) decrease, probably due to the site of protonation in this compound (as confirmed by X-ray crystal structure). X-ray crystallographic structures of two members of the series are reported. Several of these compounds have pK(a) values that would indicate potential utility for buffering at pH levels below the normal physiological range (pK(a) values in the range of 3 to 6 without aqueous solubility problems) - a range that is problematic for currently available Good buffers. Unfortunately, the alkylaminomethanesulfonates were found to degrade (with loss of their buffering ability) at pH levels below the pK(a) value and were unstable at elevated temperature (as when autoclaving) - thus limiting their utility.

In order to design the agents with improved antitumor activity of 3,5-bis(thienylidene)piperid-4-one type, E,E-N-phosphoryl-3,5-bis(thienylidene)piperid-4-ones 6a-c and E,E-N-omega-phosphorylalkyl-3,5-bis-(thienylidene)piperid-4-ones 7a-c were obtained via the direct phosphorylation of the parent NH-3,5-bis(thienylidene)piperid-4-one and by condensation of preformed N-phosphorylalkyl substituted piperidones with thiophene 2-carbaldehyde, respectively. The structures of the compounds were elucidated by (1)H, (31)P, (13)C NMR along with a single crystal X-ray diffraction analysis. Under the action of visible light thermodynamically more stable E,E-isomers slowly undergo photochemical conversion in CDCl(3) solution to the corresponding E,Z-isomers and E,Z-N-methyl-3,5-bis(thienylidene)piperid-4-one 5 was isolated in individual state. The importance of phosphorylation for cytotoxic properties of 3,5-bis(thienylidene)piperid-4-ones towards human carcinoma cell lines Caov3, Scov3, and A549 and influence of olefin configuration on antitumor activity were demonstrated., (Copyright (c) 2009 Elsevier Masson SAS. All rights reserved.)