Heraklidia A. Ioannidou

Novel BODIPY-based conjugated polymers donors for organic photovoltaic applications

Five new polymers based on the 4,4′-difluoro-4-bora-3a,4a-diaza-s-indacene core (BODIPY) chromophore moiety have been synthesized as low bandgap polymers for optoelectronic applications. The polymers exhibited high solubility in common organic solvents and optical bandgaps ranging from 1.7–2 eV. The materials were characterized using NMR, UV-Vis, steady state and time-resolved photoluminescence and the energy levels were examined using electrochemistry and validated using quantum chemical calculations. Finally, a representative BODIPY derivative : PCBM blend was examined in terms of photovoltaic properties. Preliminary device performance parameters as a function of photo-active layer thickness and composition are reported and discussed, relating to power conversion efficiency values.

Correction to "Three-Step Synthesis of Ethyl Canthinone-3-carboxylates from Ethyl 4-Bromo-6-methoxy-1,5-naphthyridine-3-carboxylate via a Pd-Catalyzed Suzuki-Miyaura Coupling and a Cu-Catalyzed Amidation Reaction".

Ethyl canthin-6-one-1-carboxylate (1b) and nine analogues 1c-k were prepared from readily prepared ethyl 4-bromo-6-methoxy-1,5-naphthyridine-3-carboxylate (2b) via a three-step non-classical approach that focused on construction of the central pyrrole (ring B) using Pd-catalyzed Suzuki-Miyaura coupling followed by Cu-catalyzed C-N coupling. Furthermore, treatment of the ethyl canthinone-1-carboxylate 1b with NaOH in DCM/MeOH (9:1) gave the canthin-6-one-1-carboxylic acid (6) in high yield. All compounds are fully characterized.

Selective Stille coupling reactions of 3-chloro-5-halo(pseudohalo)-4H-1,2,6-thiadiazin-4-ones.

A series of 3-chloro-5-halo(pseudohalo)-4H-1,2,6-thiadiazin-4-ones (halo/pseudohalo = Br, I, OTf) are prepared from 3,5-dichloro-4H-1,2,6-thiadiazin-4-one (3) in good yields. Of these the triflate reacts with tributyltin arenes (Stille couplings) chemoselectively to give only the 5-aryl-3-chloro-4H-1,2,6-thiadiazin-4-ones in high yields. This allowed the preparation of a series of unsymmetrical biaryl thiadiazines and ultimately a series of oligomers. Furthermore, treatment of 3-chloro-5-iodo-4H-1,2,6-thiadiazin-4-one (10) with Bu(3)SnH and Pd(OAc)(2) gave the bithiadiazinone which can also be further arylated via the Stille reaction to give bisthien-2-yl and bis(N-methylpyrrol-2-yl) analogs.

Ring transformation of (4-chloro-5H-1,2,3-dithiazol-5-ylidene)acetonitriles to 3-haloisothiazole-5-carbonitriles

Ring transformation of readily prepared (4-chloro-5H-1,2,3-dithiazol-5-ylidene)acetonitriles afford 3-haloisothiazole-5-carbonitriles in good to excellent yields. The transformation can be mediated using HBr (g), HCl (g) or BnEt3NCl. Mechanisms for the transformations are discussed, together with rationalizations for the formation of side products. Furthermore, single crystal X-ray structures are provided for (Z)-2-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)acetonitrile and (E)-2-bromo-2-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)acetonitrile confirming the stereochemistry of the exocyclic ethene bond.

2-(2,3,4,5,6-Pentafluorophenyl)-1H-benzo[d]imidazole, a fluorine-rich building block for the preparation of conjugated polymer donors for organic solar cell applications

We have introduced the pentafluorophenyl substituted benzimidazole as a building block of conjugated polymers for optoelectronic applications. We present the synthesis of a copolymer bearing fluorene as the comonomer. A detailed characterization of the novel material including structural, electrochemical and optical (using absorption, emission and time-resolved photoluminescence techniques) properties as well as computational modeling is described. The polymer exhibits highly efficient photoluminescence quenching when blended with fullerene derivatives (PCBM). The experimental results are compared with the alternating fluorene copolymer (APFO-3) in order to identify structure and property relations with the novel synthesized conjugated polymer. Early photovoltaic performance data are presented and compared with the well established APFO-3 : PCBM material system.

Spectroscopic characterization of C-4 substituted 3,5-dichloro-4H-1,2,6-thiadiazines

Three 3,5-dichloro-4H-1,2,6-thiadiazines, which differ according to the electron withdrawing nature of their substituent at C-4: (a) 3,5-dichloro-4-methylene-4H-1,2,6-thiadiazine (5a), (b) 3,5-dichloro-4H-1,2,6-thiadiazin-4-one (5b) and (c) 2-(3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)malononitrile (5c), are characterized using resonance Raman (RR), absorption (UV/vis) and photoluminescence (PL) spectroscopies. These weakly aromatic and electron-deficient heterocycles are potential components as acceptors in donor–acceptor systems for organic electronics. Experimental results, which include the synthesis, characterization and single crystal X-ray structure of 3,5-dichloro-4-methylene-4H-1,2,6-thiadiazine (5a), combined with theoretical calculations of their orbitals and vibrational frequencies, provide an understanding of the optical properties, on the basis of molecular geometry and electron distribution.

3,5-Bis(4-dodecylthiophen-2-yl)-4H-1,2,6-thiadiazin-4-one

Dichloro-4H-1,2,6-thiadiazin-4-one 1 reacts with (4-dodecylthiophen-2- yl)trimethylstannane 4 (2.2 equiv.) and Pd(Ph3P)2Cl2 (5 mol%) in acetonitrile at ca. 82 ° C to give 3,5-bis(4-dodecylthiophen-2-yl)-4H-1,2,6-thiadiazin-4-one 5 in 93% yield.

3-Chloro-5-(4-dodecylthiophen-2-yl)-4H-1,2,6-thiadiazin-4-one

3-Chloro-5-trifluoromethanesulfonate-4H-1,2,6-thiadiazin-4-one 3 reacts with (4-dodecylthiophen-2-yl)trimethylstannane 5 (1 equiv.) in the presence of Pd(Ph3P)2Cl2 (5 mol%) in benzene at ca. 20 °C for 5 h to give 3-chloro-5-(4-dodecylthien-2-yl)-1,2,6-thiadiazinone 6 in 87% yield.

tert-Butyl 3-(4-Cyano-5-phenylisothiazol-3-yl)carbazate

3-Iodo-5-phenylisothiazole-4-carbonitrile 1 reacts with tert-butyl carbazate via a Buchwald C-N style coupling to afford tert-butyl 3-(4-cyano-5-phenylisothiazol-3-yl)- carbazate 2 in 70% yield. [...]