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Among organic thin film transistors (OTFTs), Organic Electrochemical Transistors (OECTs) have been extensively used for cell monitoring while Electrolyte-Gated Organic Field-Effect Transistors (EGOFETs) have never been described for that kind of application. However, EGOFETs are well adapted for this use because, as well as OECTs, they can operate directly in aqueous solutions such as cells culture media, but they offer much a higher on/off ratio which could lead to better sensitivity. As a proof of concept, we propose herein to monitor the photosynthetic activity of a cyanobacterium (Anabaena flos-aquae) contained within an EGOFET's electrolyte.

The potential energy surface for the reaction of C(3Pj) with ethylene, C2H4(X1Ag), has been investigated using the G2M method. Structures of the stationary points and transition states for various isomerization and dissociation pathways of triplet C3H4 have been studied. The results show that at the initial step of the C(3Pj) + C2H4(X1Ag) reaction carbon atom attacks the π-orbital of the C2H4 molecule yielding cyclopropylidene i1 without entrance barrier. i1 then isomerizes to the triplet allene i3 via ring opening. The latter either splits a hydrogen atom producing the propargyl radical p3 + H or undergoes a 1,2-H shift to vinylmethylene, which in turn gives H2CCCH (p3) + H. The propargyl radical is concluded to be a nearly exclusive product of the C(3P) + C2H4 reaction. At the internal energy of 9.2 kcal/mol above the reactants level, Rice−Ramsperger−Kassel−Marcus calculations show about 93% of H2CCCH comes from fragmentation of triplet allene and 7% from vinylmethylene. The formation of CH2(3B1) + C2H2...

The potential energy surface for the reaction of the ground-state carbon atom [C(3Pj)] with the propargyl radical [HCCCH2(X2B1)] is investigated using the G2M(RCC,MP2) method. Numerous local minima and transition states for various isomerization and dissociation pathways of doublet C4H3 are studied. The results show that C(3Pj) attacks the π system of the propargyl radical at the acetylenic carbon atom and yields the n-C4H3(2A′) isomer i3 after an 1,2-H atom shift. This intermediate either splits a hydrogen atom and produces singlet diacetylene, [HCCCCH (p1)+H] or undergoes (to a minor amount) a 1,2-H migration to i-C4H3(2A′) i5, which in turn dissociates to p1 plus an H atom. Alternatively, atomic carbon adds to the triple CC bond of the propargyl radical to form a three-member ring C4H3 isomer i1, which ring opens to i3. Diacetylene is concluded to be a nearly exclusive product of the C(3Pj)+HCCCH2 reaction. At the internal energy of 10.0 kcal/mol above the reactant level, Rice–Ramsperger–Kassel–Marcus calculations show about 91.7% of HCCCCH comes from fragmentation of i3 and 8.3% from i5. The other possible minor channels are identified as HCCCC+H2 and C2H+HCCH. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1522–1535, 2001

The thermochemistry of c-C5H4 (3B1), c-C5H5• and c-C5H6 was investigated at the G2M(RCC,MP2) level. The heat of formation (ΔHof,298), ionization potential (IP), electron affinity (EA) and proton affinity (PA) are respectively, 125.1, 204.4, 42.5 and 230.7 kcal mol−1 for c-C5H4 (3B1), 63.5, 195.2, 44.9 and 197.2 kcal mol−1 for c-C5H5• and 32.1, 199.9, 26.0 and 195.2 kcal mol−1 for c-C5H6. The computed values for the last two molecules are in excellent agreement with available experimental data, with the errors of ±1 and ±2 kcal mol−1 for the heat of formation and the other parameters, respectively. In addition, the heat of formation of c-C5H4•− is evaluated as 82.0 kcal mol−1, about 10 kcal mol−1 higher than the experimental value. This leads to the suggestion that the experimental ΔHof,298(c-C5H4•−) value needs to be re-examined. Copyright © 2001 John Wiley & Sons, Ltd.

Heats of formation of spiropentadiene, spiropentane and bicyclo[1.1.0]but-1(3)-ene have been calculated employing the G2M(RCC,MP2) method. The values obtained using 27, 8 and 10 different working reactions are 150.5, 43.0 and 133.0 kcal/mol for spiropentadiene, spiropentane and bicyclo[1.1.0]but-1(3)-ene, respectively, with the error bars estimated as ±2 kcal/mol. The results are in close agreement with available experimental data and allow to resolve the persisting uncertainties in the heats of formation of the simplest bicyclic hydrocarbons.

More than thirty equilibrium and transition structures on the [CH3NS] potential energy surface have been located using the B3LYP/6-311 + + G(d,p) method. Thioformaldoxime (3) turns out to be the most stable isomer followed by thionitrone (2), a three-membered ring, thionitrosyl methane (1) and thiazyl methane. These isomers are connected to each other by 1,2H and 1,3H shifts and ring—chain rearrangement, but the associated energy barriers are rather high, making most of them stable with respect to unimolecular transformations. Starting from CH3 + NS, a possible initial atmospheric reaction, HCN formation appears to be the most favoured process through a cascade involvement of 1, 2 and 3. The standard heats of formation, ΔH 0 f,298 are calculated to be: 3, 149kJmol−1; and 1, 218kJmol−1; using the CCSD(T)/6-311+ +G(3df,2p) method, with an error of ±10kJ mol−1.

The reactions of hydrogen isocyanide (HN⋮C) with various simple alkynes (HC⋮C−X, with X = H, CH3, NH2, F), formally [2 + 1] cycloadditions, have been studied by density functional theory (DFT) with the hybrid exchange correlation B3LYP functional and a 6-311G(d,p) basis set, as well as by MO theory with CCSD(T) calculations. For each reaction, the intrinsic reaction coordinate (IRC) pathway has been constructed. It is shown that each [2 + 1] cycloaddition is nonconcerted but proceeds in two steps: rate-determining addition of HN⋮C to a carbon atom of HC⋮CX, giving rise to a zwitterion intermediate, followed by a ring closure of the latter, yielding finally cyclopropenimine. In all cases, HN⋮C behaves as an electrophile. The activation energies corresponding to both possible initial attacks of HN⋮C are distinguishable, introducing thus a site selectivity and an asynchronism of bond formation in the initial step, for which a rationalization using DFT-based reactivity descriptors and the local HSAB principl...

The cycloaddition reactions of 1,3-dipoles, including fulminic acid (HCNO) and the simple azides (XNNN, X = H,CH3,NH2), with thionitroso compounds (R–NS, R = H, NH2) as dipolarophiles have been studied by density function procedures using the hybrid B3LYP exchange correlation function and 6–311G(d,p) basis functions. For each system, two (HCNO) or four (azide) distinct transition structures have been located and the intrinsic reaction coordinate path was constructed. It appears in all cases that activation energies for the cycloadditions are rather low, ranging from 0 to 30 kJ mol–1. The additions are not stereospecific, the energy difference between transition structures having cis and trans dispositions of the N–R groups being rather small (less than a few kJ mol–1). The addition shows a certain regioselectivity in which the attack of the O-atom of HCNO and N(R) of the azides to the S-atom of the dipolarophile is preferred. This regiochemistry is explained using recently developed DFT-based reactivity descriptors, such as local softness and Fukui functions. The hardness and polarizability profiles of the supersystem along the IRC paths were also discussed.

The potential-energy surface related to the H2N+NS reaction, which involves 13 intermediates and fragment products, as well as 14 transition structures has been fully characterized using both molecular orbital (MP2) and density functional theory (B3LYP) and the 6-311++G(d,p) basis set. Improved electronic energies have also been obtained using single-point coupled-cluster CCSD(T) calculations. The system is shown to have three different groups of products: N2H+SH, N2S+H2 and N2+H2S and a rather complex reaction mechanism. Starting from H2N+NS, several low-lying [H2N2S] isomers participate in the elimination of H2 and N2. The N2 elimination appears to be favoured over other reaction channels in the destruction of NS. The standard enthalpies of formation of the most stable isomers have been estimated, ΔfH298° in kJ mol-1: H2N–NS: 250, H2N–S▷N: 262, NHNHS: 264, NHN–SH: 247 and NHSNH: 318.

Crossed molecular beam experiments on dicarbon and tricarbon reactions with unsaturated hydrocarbons acetylene, methylacetylene, and ethylene were performed to investigate the dynamics of channels leading to hydrogen-deficient hydrocarbon radicals. In the light of the results of new ab initio calculations, the experimental data suggest that these reactions are governed by an initial addition of C2/C3 to the pi molecular orbitals forming highly unsaturated cyclic structures. These intermediates are connected via various transition states and are suggested to ring open to chain isomers which decompose predominantly by displacement of atomic hydrogen, forming C4H, C5H, HCCCCCH2, HCCCCCCH3, H2CCCCH and H2CCCCCH. The C2(1 sigma g+) + C2H4 reaction has no entrance barrier and the channel leading to the H2CCCCH product is strongly exothermic. This is in strong contrast with the C3(1 sigma g+) + C2H4 reaction as this is characterized by a 26.4 kJ mol-1 threshold to form a HCCCCCH2 isomer. Analogous to the behavior with ethylene, preliminary results on the reactions of C2 and C3 with C2H2 and CH3CCH showed the H-displacement channels of these systems to share many similarities such as the absence/presence of an entrance barrier and the reaction mechanism. The explicit identification of the C2/C3 vs. hydrogen displacement demonstrates that hydrogen-deficient hydrocarbon radicals can be formed easily in environments like those of combustion processes. Our work is a first step towards a systematic database of the intermediates and the reaction products which are involved in this important class of reactions. These findings should be included in future models of PAH and soot formation in combustion flames.