Low-oxidation-potential thiophene-carbazole monomers for electro-oxidative molecular imprinting: Selective chemosensing of aripiprazole.

New thiophene-carbazole functional and cross-linking monomers electropolymerizing at potentials sufficiently low for molecular imprinting of an electroactive aripiprazole antipsychotic drug were herein designed and synthesized. Numerous conducting molecularly imprinted polymer (MIP) films are deposited by electropolymerization at relatively low potentials by electro-oxidation of pyrrole, aniline, phenol, or 3,4-ethylenedioxythiophene (EDOT). However, their interactions with templates are not sufficiently strong. Hence, it is necessary to introduce additional recognizing sites in these cavities to increase their affinity to the target molecules. For that, functional monomers derivatized with substituents forming stable complexes with the templates are used. However, oxidation potentials of these derivatives are often, disadvantageously, higher than that of parent monomers. Therefore, we designed and synthesized new functional and cross-linking monomers, which are oxidized at sufficiently low potentials. The deposited MIP and non-imprinted polymer (NIP) films were characterized by PM-IRRAS and UV-vis spectroscopy and imaged with AFM. The structure of the aripiprazole pre-polymerization complex with functional monomers was optimized with density functional theory (DFT), and aripiprazole interactions with imprinted cavities were simulated with molecular mechanics (MM) and molecular dynamics (MD). MIP-aripiprazole film-coated electrodes were used as extended gates for selective determination of aripiprazole with the extended-gate field-effect transistor (EG-FET) chemosensor. The linear dynamic concentration range was 30-300 pM, and the limit of detection was 22 fM. An apparent imprinting factor of the MIP-1 was IF = 4.95. The devised chemosensor was highly selective to glucose, urea, and creatinine interferences. The chemosensor was successfully applied for aripiprazole determination in human plasma. The results obtained were compared to those of the validated HPLC-MS method.

Fluorinated Porphycenes: Synthesis, Spectroscopy, Photophysics, and Tautomerism.

Six porphycenes have been synthesized, bearing one, two, or three fluorine atoms attached directly to the 18-π-electron system at the meso positions. These novel compounds have been characterized by structural, electrochemical, and spectral techniques, combined with quantum chemical calculations. In three fluoroporphycenes, the unsymmetric substitution pattern leads to the presence of two nonequivalent trans tautomeric forms. They have been identified using electronic absorption, emission, and magnetic circular dichroism spectroscopies. Their relative energies have been estimated for the ground and lowest excited electronic states. Tautomerization potential is quasi-symmetric in S0 , but becomes strongly nonsymmetric in S1 . Femtosecond transient absorption studies allowed determination of tautomerization rates, larger and similar for both directions of the double hydrogen transfer in S0 , lower and disparate in S1 . Fluoroporphycenes emerge as good candidates for detailed studies of mechanisms of double hydrogen transfer, as well as processes responsible for rapid radiationless excited state depopulation.

Low and High Molecular Mass Dithienopyrrole-Naphthalene Bisimide Donor-Acceptor Compounds: Synthesis, Electrochemical and Spectroelectrochemical Behaviour.

Two low molecular weight electroactive donor-acceptor-donor (DAD)-type molecules are reported, namely naphthalene bisimide (NBI) symmetrically core-functionalized with dithienopyrrole (NBI-(DTP)2 ) and an asymmetric core-functionalized naphthalene bisimide with dithienopyrrole (DTP) substituent on one side and 2-ethylhexylamine on the other side (NBI-DTP-NHEtHex). Both compounds are characterized by low optical bandgaps (1.52 and 1.65 eV, respectively). NBI-(DTP)2 undergoes oxidative electropolymerization giving the electroactive polymer of ambipolar character. Its two-step reversible reduction and oxidation is corroborated by complementary EPR and UV/Vis-NIR spectroelectrochemical investigations. The polymer turned out to be electrochemically active not only in aprotic solvents but also in aqueous electrolytes, showing a distinct photocathodic current attributed to proton reduction. Additionally, poly(NBI-(DTP)2 ) was successfully tested as a photodiode material.

Naphthalene bisimides asymmetrically and symmetrically N-substituted with triarylamine--comparison of spectroscopic, electrochemical, electronic and self-assembly properties.

Two semiconducting naphthalene bisimides were comparatively studied: NBI-(TAA)(2), symmetrically N-substituted with triaryl amine and asymmetric NBI-TAA-Oc with triaryl amine and octyl N-substituents. Both compounds show very similar spectroscopic and redox properties but differ in their supramolecular organization. As evidenced by STM, in monolayers on HOPG they form ordered 2D structures, however of different packing patterns. NBI-(TAA)(2) does not form ordered 3D structures, yielding amorphous thin films whereas films of NBI-TAA-Oc are highly crystalline. DFT calculations predict the ionization potential (IP) of 5.22 eV and 5.18 eV for NBI-TAA-Oc and NBI-(TAA)(2), respectively, as well as the electron affinity values (EA) of -3.25 eV and -3.22 eV. These results are consistent with the cyclic voltammetry data which yield similar values of IP (5.20 eV and 5.19 eV) and somehow different values of EA (-3.80 eV and -3.83 eV). As judged from these data, both semiconductors should exhibit ambipolar behavior. Indeed, NBI-TAA-Oc is ambipolar, showing hole and electron mobilities of 4.5 × 10(-5) cm(2)/(V s) and of 2.6 × 10(-4) cm(2)/(V s), respectively, in the field effect transistor configuration. NBI-(TAA)(2) is not ambipolar and yields field effect only in the p-channel configuration. This different behavior is rationalized on the basis of structural factors.