13-Nitro-benzo[a][1,4]benzo-thia-zino[3,2-c]phenoxazine.

In the title compound, C22H11N3O3S, dihedral angle between the phenyl rings on the periphery of the molecule is 8.05 (18)°. In the crystal, aromatic π-π stacking distance and short C-H⋯O contacts are observed. The maximum absorption occurs at 688 nm.

Benzo[a][1,4]benzothia-zino[3,2-c]phenothia-zine.

The title compound, C22H12N2S2, crystallizes in space group P21/c with four mol-ecules in the asymmetric unit. The heterocyclic mol-ecule is quasi-planar with a dihedral angle between the phenyl rings on the periphery of the mol-ecule of 1.73 (19)°. Short H⋯S (2.92 Å) and C-H⋯π [2.836 (3) Å] contacts are observed in the crystal with shorted π-π stacking distances of 3.438 (3) Šalong the b axis. Surprisingly, and unlike a closely related material, this mol-ecule readily forms large crystals by sublimation and by slow evaporation from di-chloro-methane. The maximum absorbance in the UV-Vis spectrum is at 533 nm. Emission was measured upon excitation at 533 nm with a fluorescence λmax of 658 nm and cutoff of 900 nm.

Di- and Tricyanovinyl-Substituted Triphenylamines: Structural and Computational Studies.

We report herein on the solid-state structures of three closely related triphenylamine derivatives endowed with tricyanovinyl (TCV) and dicyanovinyl (DCV) groups. The molecules described contain structural features commonly found in the design of functional organic materials, especially donor-acceptor molecular and polymeric architectures. The common feature noticeable in these structures is the impact of these exceptionally strong electron-accepting groups in forcing partial planarity of the portion of the molecule carrying these groups and directing the molecular packing in the solid state, resulting in the formation of π-stacks of dimers within the unit cell of each. Stacks are formed between phenyl groups bearing electron-accepting groups on two adjacent molecules. Short π-π stack distances ranging from 3.283 to 3.671 Å were observed. Such motif patterns are thought to be conducive for better charge transport in organic semiconductors and enhanced device performance. Intramolecular charge transfer is evident from the shortening of the observed experimental bond lengths in all three compounds. The nitrogen atoms (of the cyano groups) have been shown to be extensively involved in short contacts in all three structures, primarily through C-H···NC interactions with distances as short as 2.462 Å. The compounds reported here are (3,3-dicyano-2-(4-(diphenylamino)phenyl)-1λ3-allylidene)amide or tricyanovinyltriphenylamine, Ph3NTCV (1); 2-(4-(diphenylamino)benzylidene)-malononitrile or dicyanovinyltriphenylamine, Ph3NDCV (2); and (3,3-dicyano-2-(4-(di-p-tolylamino)phenyl)-1λ3-allylidene)amide or dimethyltricyanovinyltriphenylamine, Me2Ph3NTCV (3). Results of density functional theory calculations using DFT-B3LYP/6-31G(d,p) indicate the lowering of LUMO levels as a result of the introduction of these groups with band gaps of 3.13, 2.61, and 2.55 eV for compounds 1-3, respectively, compared with 4.65 eV calculated for triphenylamine. This is supported by the electronic and fluorescence spectra of these molecules with absorption λmax of 483, 515, and 545 nm for compounds 1, 2, and 3, respectively.

Crystal structure of 1-{4-[bis-(4-methyl-phen-yl)amino]-phen-yl}ethene-1,2,2-tricarbo-nitrile.

The title compound, C25H18N4, crystallizes in the centrosymmetric ortho-rhom-bic space group Pbca, with eight mol-ecules in the unit cell. The main feature noticeable in the structure is the impact of the tri-cyano-vinyl (TCV) group in forcing partial planarity of the portion of the mol-ecule carrying the TCV group and directing the mol-ecular packing in the solid state, resulting in the formation of π-stacks of dimers within the unit cell. Short π-π stack closest atom-to-atom distances of 3.444 (15) Šare observed. Such motif patterns are favorable as they are thought to be conducive for better charge transport in organic semiconductors, which results in enhanced device performance. Intra-molecular charge transfer is evident from the shortening in the observed experimental bond lengths. The nitro-gen atoms (of the cyano groups) are involved in extensive short contacts, primarily through C-H⋯NC inter-actions with distances of 2.637 (17) Å.

Multi-analyte biochip (MAB) based on all-solid-state ion-selective electrodes (ASSISE) for physiological research.

Lab-on-a-chip (LOC) applications in environmental, biomedical, agricultural, biological, and spaceflight research require an ion-selective electrode (ISE) that can withstand prolonged storage in complex biological media (1-4). An all-solid-state ion-selective-electrode (ASSISE) is especially attractive for the aforementioned applications. The electrode should have the following favorable characteristics: easy construction, low maintenance, and (potential for) miniaturization, allowing for batch processing. A microfabricated ASSISE intended for quantifying H(+), Ca(2+), and CO3(2-) ions was constructed. It consists of a noble-metal electrode layer (i.e. Pt), a transduction layer, and an ion-selective membrane (ISM) layer. The transduction layer functions to transduce the concentration-dependent chemical potential of the ion-selective membrane into a measurable electrical signal. The lifetime of an ASSISE is found to depend on maintaining the potential at the conductive layer/membrane interface (5-7). To extend the ASSISE working lifetime and thereby maintain stable potentials at the interfacial layers, we utilized the conductive polymer (CP) poly(3,4-ethylenedioxythiophene) (PEDOT) (7-9) in place of silver/silver chloride (Ag/AgCl) as the transducer layer. We constructed the ASSISE in a lab-on-a-chip format, which we called the multi-analyte biochip (MAB) (Figure 1). Calibrations in test solutions demonstrated that the MAB can monitor pH (operational range pH 4-9), CO3(2-) (measured range 0.01 mM - 1 mM), and Ca(2+) (log-linear range 0.01 mM to 1 mM). The MAB for pH provides a near-Nernstian slope response after almost one month storage in algal medium. The carbonate biochips show a potentiometric profile similar to that of a conventional ion-selective electrode. Physiological measurements were employed to monitor biological activity of the model system, the microalga Chlorella vulgaris. The MAB conveys an advantage in size, versatility, and multiplexed analyte sensing capability, making it applicable to many confined monitoring situations, on Earth or in space. Biochip Design and Experimental Methods The biochip is 10 x 11 mm in dimension and has 9 ASSISEs designated as working electrodes (WEs) and 5 Ag/AgCl reference electrodes (REs). Each working electrode (WE) is 240 µm in diameter and is equally spaced at 1.4 mm from the REs, which are 480 µm in diameter. These electrodes are connected to electrical contact pads with a dimension of 0.5 mm x 0.5 mm. The schematic is shown in Figure 2. Cyclic voltammetry (CV) and galvanostatic deposition methods are used to electropolymerize the PEDOT films using a Bioanalytical Systems Inc. (BASI) C3 cell stand (Figure 3). The counter-ion for the PEDOT film is tailored to suit the analyte ion of interest. A PEDOT with poly(styrenesulfonate) counter ion (PEDOT/PSS) is utilized for H(+) and CO3(2-), while one with sulphate (added to the solution as CaSO4) is utilized for Ca(2+). The electrochemical properties of the PEDOT-coated WE is analyzed using CVs in redox-active solution (i.e. 2 mM potassium ferricyanide (K3Fe(CN)6)). Based on the CV profile, Randles-Sevcik analysis was used to determine the effective surface area (10). Spin-coating at 1,500 rpm is used to cast ~2 µm thick ion-selective membranes (ISMs) on the MAB working electrodes (WEs). The MAB is contained in a microfluidic flow-cell chamber filled with a 150 µl volume of algal medium; the contact pads are electrically connected to the BASI system (Figure 4). The photosynthetic activity of Chlorella vulgaris is monitored in ambient light and dark conditions.

(1E,3E,5E,7E)-4,4'-(Octa-1,3,5,7-tetra-ene-1,8-di-yl)dipyridine.

The title compound, C(18)H(16)N(2), crystallizes with one and a half independent mol-ecules in the asymmetric unit, with the half-mol-ecule being completed by crystallographic inversion symmetry. Both independent mol-ecules are almost planar, with the non-H atoms exhibiting r.m.s. deviations from the least-squares mol-ecular plane of 0.175 and 0.118 Å, respectively.

4-[(1E,3E,5E)-6-(4-Pyrid-yl)hexa-1,3,5-trien-yl]pyridine.

The two independent mol-ecules in the asymmetric unit of the title compound, C(16)H(14)N(2), are planar [dihedral angle between the terminal pyridine rings = 1.76 (2)°] and each display an all-trans configuration of C=C double bonds. One of the two mol-ecules lies about a center of inversion. The dihedral angle between the two pyridine rings in the mol-ecule lying on a general position is 1.65 (2)°.

2,5-Bis(5-bromo-2-thien-yl)thio-phene.

In the crystal structure of the title compound, C(12)H(6)Br(2)S(3), the mol-ecules are planar (r.m.s. deviation = 0.06 Å). Consecutive mol-ecules do not stack in a planar fashion. There is an angle of 81.7 (12)° between the planes of the closest mol-ecules.

N- and P-channel transport behavior in thin film transistors based on tricyanovinyl-capped oligothiophenes.

We report the structural and electrical characterization of thin films of organic semiconductor molecules consisting of an oligothiophene core capped with electron-withdrawing tricyanovinyl (TCV) groups. X-ray diffraction and atomic force microscopy of evaporated films of three different TCV-capped oligothiophenes showed that the films were highly crystalline. Electrical transport was measured in thin film transistors employing silver source and drain contacts and channel probes to correct for contact resistance. Three compounds exhibited n-channel (electron) conduction consistent with cyclic voltametry data that indicated they undergo facile reduction. Maximum electron mobilities were 0.02 cm2/V.s with an on/off current ratio of 10(6). A fourth end-capped molecule, TCV-6T-TCV, which had six thiophene rings, exhibited both p- and n-channel transport. Overall, these results confirm that substitution of oligothiophene cores with electron-withdrawing groups is a useful strategy to achieve electron-transporting materials.