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

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

Unraveling Unprecedented Charge Carrier Mobility through Structure Property Relationship of Four Isomers of Didodecyl[1]benzothieno[3,2-b][1]benzothiophene.

The structural and electronic properties of four isomers of didodecyl[1]-benzothieno[3,2-b][1]benzothiophene (C12-BTBT) have been investigated. Results show the strong impact of the molecular packing on charge carrier transport and electronic polarization properties. Field-induced time-resolved microwave conductivity measurements unravel an unprecedented high average interfacial mobility of 170 cm(2) V(-1) s(-1) for the 2,7-isomer, holding great promise for the field of organic electronics.

Bulky end-capped [1]benzothieno[3,2-b]benzothiophenes: reaching high-mobility organic semiconductors by fine tuning of the crystalline solid-state order.

A series of bulky end-capped [1]benzothieno[3,2-b]benzothiophenes (BTBTs) are developed in order to tune the packing structure via terminal substitution. A coupled theoretical and experimental study allows us to identify 2,7-di-tert-butylBTBT as a new high-performance organic semiconductor with large and well-balanced transfer integrals, as evidenced by quantum-chemical calculations. Single-crystal field-effect transistors show a remarkable average saturation mobility of 7.1 cm(2) V(-1) s(-1) .

Semi-metallic polymers.

Polymers are lightweight, flexible, solution-processable materials that are promising for low-cost printed electronics as well as for mass-produced and large-area applications. Previous studies demonstrated that they can possess insulating, semiconducting or metallic properties; here we report that polymers can also be semi-metallic. Semi-metals, exemplified by bismuth, graphite and telluride alloys, have no energy bandgap and a very low density of states at the Fermi level. Furthermore, they typically have a higher Seebeck coefficient and lower thermal conductivities compared with metals, thus being suitable for thermoelectric applications. We measure the thermoelectric properties of various poly(3,4-ethylenedioxythiophene) samples, and observe a marked increase in the Seebeck coefficient when the electrical conductivity is enhanced through molecular organization. This initiates the transition from a Fermi glass to a semi-metal. The high Seebeck value, the metallic conductivity at room temperature and the absence of unpaired electron spins makes polymer semi-metals attractive for thermoelectrics and spintronics.

High Mobility in Solution-Processed 2,7-Dialkyl-[1]benzothieno[3,2-b][1]benzothiophene-Based Field-Effect Transistors Prepared with a Simplified Deposition Method.

A high performing solution-processed field-effect transistors based on 2,7-didodecyl[1]benzothieno[3,2-b][1]benzothiophene (C12-BTBT) has been fabricated by using a simple and straightforward two-step process. We have demonstrated that UV/ozone treatment of the Si/SiO2 substrates makes it possible to notably enhance the field-effect mobility in spin-coated C12-BTBT based OFETs reaching values as high as 2.7 cm2 V-1 s-1 . The influence of this treatment relies essentially on the coverage of the dielectric surface, while the crystalline order remains unaffected. Importantly, the employed method is simple, cheap and easily up-scalable and provides outstanding OFET performances that are comparable to those obtained using expensive and complicated treatments.

Absorbing a Little Water: The Structural, Thermodynamic, and Kinetic Relationship between Pyrogallol and Its Tetarto-Hydrate.

The anhydrate and the stoichiometric tetarto-hydrate of pyrogallol (0.25 mol water per mol pyrogallol) are both storage stable at ambient conditions, provided that they are phase pure, with the system being at equilibrium at aw (water activity) = 0.15 at 25 °C. Structures have been derived from single crystal and powder X-ray diffraction data for the anhydrate and hydrate, respectively. It is notable that the tetarto-hydrate forms a tetragonal structure with water in channels, a framework that although stabilized by water, is found as a higher energy structure on a computationally generated crystal energy landscape, which has the anhydrate crystal structure as the most stable form. Thus, a combination of slurry experiments, X-ray diffraction, spectroscopy, moisture (de)sorption, and thermo-analytical methods with the computationally generated crystal energy landscape and lattice energy calculations provides a consistent picture of the finely balanced hydration behavior of pyrogallol. In addition, two monotropically related dimethyl sulfoxide monosolvates were found in the accompanying solid form screen.

Doping of organic semiconductors: impact of dopant strength and electronic coupling.

Molecular doping: The standard model for molecular p-doping of organic semiconductors (OSCs) assumes integer charge transfer between OSC and dopant. This is in contrast to an alternative model based on intermolecular complex formation instead. By systematically varying the acceptor strength it was possible to discriminate the two models. The latter is clearly favored, suggesting strategies for the chemical design of more efficient molecular dopants.

Synthesis and characterization of isomerically pure anti- and syn-anthradiindole derivatives.

Synthesis, isolation, and characterization of isomerically pure syn- and anti-anthradiindole (ADI) derivatives are described. The anti- and syn-ADI structures are demonstrated by (13)C NMR spectroscopy and by single-crystal X-ray diffraction. The spectroscopic and electrochemical properties as well as the stability of these newly synthesized π-conjugated systems are evaluated and supported by quantum-chemical calculations.

Alkaline earth metal salts of 1-naphthoic acid.

The structures of the Mg, Ca, Sr and Ba salts of 1-naphthoic acid are examined and compared with analogous structures of salts of benzoate derivatives. It is shown that catena-poly[[[diaquabis(1-naphthoato-κO)magnesium(II)]-µ-aqua] dihydrate], {[Mg(C(11)H(7)O(2))(2)(H(2)O)(3)]·2H(2)O}(n), exists as a one-dimensional coordination polymer that propagates only through Mg-OH(2)-Mg interactions along the crystallographic b direction. In contrast with related benzoate salts, the naphthalene systems are large enough to prevent inorganic chain-to-chain interactions, and thus species with inorganic channels rather than layers are formed. The Ca, Sr and Ba salts all have metal centres that lie on a twofold axis (Z' = 1/2) and all have the common name catena-poly[[diaquametal(II)]-bis(µ-1-naphthoato)-κ(3)O,O':O;κ(3)O:O,O'], [M(C(11)H(7)O(2))(2)(H(2)O)(2)](n), where M = Ca, Sr or Ba. The Ca and Sr salts are essentially isostructural, and all three species form one-dimensional coordination polymers through a carboxylate group that forms three M-O bonds. The polymeric chains propagate via c-glide planes and through MOMO four-membered rings. Again, inorganic channel structures are formed rather than layered structures, and the three structures are similar to those found for Ca and Sr salicylates and other substituted benzoates.

Magnesium, calcium and strontium salts of phenylacetic acid.

Three alkaline earth metal salts of phenylacetic acid were examined and all were found to have similar structural types to analogous salts of benzoic and halobenzoic acids. Thus, a synchrotron study shows that the cations in catena-poly[[[tetraaquamagnesium(II)]-µ-phenylacetato-κ(2)O:O'] phenylacetate], {[Mg(C(8)H(7)O(2))(H(2)O)(4)](C(8)H(7)O(2))}(n), form a one-dimensional coordination polymer that propagates through Mg-O-C-O-Mg interactions involving both crystallographically independent Mg centres (Z' = 2) and through translation along the a axis. The polymeric chains pack to give alternate inorganic layers and organic bilayers. The Ca and Sr species catena-poly[[[diaqua(phenylacetato-κ(2)O,O')calcium(II)]-µ(3)-phenylacetato-1':1:1''κ(4)O:O,O':O'] monohydrate], {[Ca(C(8)H(7)O(2))(2)(H(2)O)(2)]·H(2)O}(n), and catena-poly[[[diaqua(phenylacetato-κ(2)O,O')strontium(II)]-µ(3)-phenylacetato-1':1:1''κ(4)O:O,O':O'] monohydrate], {[Sr(C(8)H(7)O(2))(2)(H(2)O)(2)]·H(2)O}(n), are essentially isostructural. Both form one-dimensional coordination polymers through a carboxylate group that forms four M-O bonds. The polymeric chains propagate via 2(1) screw axes parallel to the b axis and are further linked in the bc plane by hydrogen bonding involving the non-metal-bound water molecule. Similarly to the Mg salt, both have inorganic layers that alternate with organic bilayers.

A strategy for producing predicted polymorphs: catemeric carbamazepine form V.

A computationally assisted approach has enabled the first catemeric polymorph of carbamazepine (form V) to be selectively formed by templating the growth of carbamazepine from the vapour phase onto the surface of a crystal of dihydrocarbamazepine form II.

Intermolecular interactions, disorder and twinning in ciprofloxacin-2,2-difluoroethanol (2/3) and ciprofloxacin-water (3/14.5).

The antibiotic ciprofloxacin [systematic name: 1-cyclopropyl-6-fluoro-4-oxo-7-(piperazin-4-ium-1-yl)-1,4-dihydroquinoline-3-carboxylate], has been crystallized as a 2:3 solvate with 2,2-difluoroethanol, 2C(17)H(18)FN(3)O(3)·3C(2)H(4)O(2), (I), and as a 3:14.5 hydrate, 3C(17)H(18)FN(3)O(3)·14.5H(2)O, (II). The structure of (I) was determined using synchrotron X-ray diffraction data and refined as a two-component nonmerohedral twin. Both structures contain several independent molecules in the asymmetric unit: (I) contains two zwitterionic ciprofloxacin molecules and three difluoroethanol solvent molecules, while (II) contains three zwitterionic ciprofloxacin molecules and a mixture of ordered and disordered water molecules. The intermolecular interactions were analysed using fingerprint plots derived from Hirshfeld surfaces, providing a detailed description of the unique environment of each independent ciprofloxacin molecule.

Solid-State Forms of ß-Resorcylic Acid: How Exhaustive Should a Polymorph Screen Be?

An extensive experimental screen, coupled with a computational study, revealed seven new solid-state forms of ß-resorcylic acid. The known, stable polymorph II° shows a reversible phase transformation to the new, kinetically stable, probably disordered high temperature form I. The study provides a consistent picture of the solid-state of ß-resorcylic acid.

Supramolecular structure in s-block metal complexes of sulfonated monoazo dyes: discrepant packing and bonding behavior of ortho-sulfonated azo dyes.

The first solid-state structures of ortho-sulfonated monoazo dyestuffs are reported and compared to those of their para- and meta-sulfonated analogues. The structures of the 16 Na, K, Cs, Mg, Ca, Sr, and Ba ortho-sulfonated salts are found to have fewer M-O(3)S bonds than their isomeric equivalents and this in turn means that the metal type is no longer the prime indicator of which structural type will be adopted. M-O(3)S bonds are replaced by M-OH(2), M-HOR and M-pi interactions, apparently for steric reasons. As well as new bonding motifs, the changed dye shape also leads to new packing motifs. The simple organic/inorganic layering ubiquitous to the para- and meta-sulfonated dye salt structures is replaced by variations (organic bilayers, inorganic channels), each of which correlates with a different degree of molecular planarity in the sulfonated azo dye anion.

3-Amino-carbonyl-pyridinium difluoro-acetate at 123†K.

In the crystal of the title compound, C(6)H(7)N(2)O(+)·C(2)HF(2)O(2) (-), the cation adopts a catemeric N-H⋯O hydrogen-bonded chain motif involving the carboxamide group, with two further N-H⋯O hydrogen bonds connecting the cations to adjacent difluoro-acetate anions via the carboxamide and pyridinium N atoms. The carboxamide group of the nicotinamidium ion is twisted by 32.3 (6)° from the pyridine ring plane. A number of C-H⋯O and C-H⋯F interactions consolidate the packing.

Lithium aspirinate hemihydrate.

The title compound {systematic name: catena-poly[lithium(I)-mu3-acetylsalicylato-hemi-mu2-aqua]}, {[Li(C9H7O4)] x 0.5 H2O}n, is the hemihydrate of the lithium salt of aspirin. The carboxylate groups and water molecules bridge between Li atoms to form a one-dimensional coordination chain composed of two distinct ring types. The water O atom lies on a twofold axis. Hydrogen bonding between water donors and carbonyl acceptors further links the coordination chains to form a sheet structure.