Synthesis, Photophysical, and (Spectro)Electrochemical Properties of New Benzo[1,2-][1,2,5]thiadiazoles and Benzo[1,2-][1,2,3]triazoles Fused with Two Thiazole Rings.

Acylation of benzo[][1,2,5]thiadiazole-4,7-diamine and 2-hexyl-2-benzo[][1,2,3]triazole-4,7-diamine with aromatic acid halides furnished the corresponding ,'-diamides, which were converted into ,'-dithioamides by reacting with Lawesson's reagent. A method was developed for the preparation of previously unknown fused systems, dithiazolobenzo[1,2-][1,2,5]thiadiazoles and dithiazolobenzo[1,2-][1,2,3]triazoles, by oxidative photochemical cyclization of ,'-dithioamides. The photophysical and (spectro)electrochemical properties of the obtained compounds and their polymer films electrochemically deposited on ITO were studied.

Photochemical Synthesis and Electrochemical and Photophysical Properties of 2,7-Diarylbenzo[1,2-d:4,3-d']bis(thiazoles).

This article focuses on the development of practical approaches to the preparation of benzo[1,2-:4,3-']bis(thiazoles) using blue light-induced photochemical cyclization of '-(1,4-aryl)dithioamides in the presence of -chloranil as a mild oxidant. The proposed method allows to obtain benzo[1,2-:4,3-']bis(thiazoles) containing donor substituents in the conjugated chain. Photophysical and (spectro)electrochemical properties of 2,6-di([2,2'-bithiophen]-5-yl)benzo[1,2-:4,3-]bis(thiazole) and -benzo[1,2-:4,5-']bis(thiazole) are studied in detail.

Rearrangement of 7-Aryloxazolo[5,4-]pyridines to Benzo[][1,7]naphthyridine-4(3)-ones and Thieno[3,2-][1,7]naphthyridine-6(7)-ones.

In this work, we describe the development of the rearrangement for 7-aryl-substituted oxazolo[5,4-]pyridines treated with aluminum chloride into synthetically hard-to-reach benzo[][1,7]naphthyridinones. The discovered rearrangement is applied to a variety of electron-rich (hetero)arene substrates. It offers the advantages of mild conditions (90 °C temperature), fast reaction rates (<4 h), compatibility with air moisture, and the use of inexpensive commercial reagents.

Synthesis of Bis([2,2'-bithiophen]-5-yl)-Substituted Oligothiadiazoles: Effect of the Number of Acceptor Units on Electrochemical and Spectroscopic Properties.

1,3,4-Thiadiazole, 2,2'-bi(1,3,4-thiadiazole), 2,2':5',2″-ter(1,3,4-thiadiazole), and 2,2':5',2″:5″,2‴-quater(1,3,4-thiadiazole) symmetrically disubstituted with 3-alkyl-(2,2'-bithiophen)-5-yl were synthesized by new procedures using readily available ethyl 3-alkyl-(2,2'-bithiophene)-5-carboxylate as a convenient substrate. These new compounds with a fixed number of donor rings and increasing number of acceptor rings showed very interesting, tunable redox properties. In particular, they exhibited electron affinities (EAs) ranging from -3.

Effect of donor to acceptor ratio on electrochemical and spectroscopic properties of oligoalkylthiophene 1,3,4-oxadiazole derivatives.

A structure-property study across a series of donor-acceptor-donor structures composed of mono- and bi-(1,3,4-oxadiazole) units symmetrically substituted with alkyl functionalized bi-, ter- and quaterthiophene segments is presented. Synthetically tailoring the ratio of electron-withdrawing 1,3,4-oxadiazole to electron-releasing thiophene units and their alkyl grafting pattern permitted us to scrutinize the impact of these structural factors on the redox, absorptive and emissive properties of these push-pull molecules. Contrasting trends of redox potentials were observed, with the oxidation potential closely following the donor-to-acceptor ratio, whereas the reduction potential being tuned independently by either the number of acceptor units or the conjugation length of the donor-acceptor system.

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles.

New photoluminescent donor-acceptor-donor (DAD) molecules, namely 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles were prepared by palladium-catalyzed coupling from readily available compounds such as ethyl 3-decyl-2,2'-bithiophene-5-carboxylate and aryl halides. The obtained compounds feature increasing bathochromic shifts in their emission spectra with increasing aryl-substituent size yielding blue to bluish-green emissions. At the same time, their absorption spectra are almost independent from the identity of the terminal substituent with λ values ranging from 395 to 405 nm.

Star-Shaped Conjugated Molecules with Oxa- or Thiadiazole Bithiophene Side Arms.

Star-shaped conjugated molecules, consisting of a benzene central unit symmetrically trisubstituted with either oxa- or thiadiazole bithiophene groups, were synthesized as promising molecules and building blocks for application in (opto)electronics and electrochromic devices. Their optical (Eg (opt)) as well as electrochemical (Eg (electro)) band gaps depended on the type of the side arm and the number of solubilizing alkyl substituents. Oxadiazole derivatives showed Eg (opt) slightly below 3 eV and by 0.

Synthesis of new, highly luminescent bis(2,2'-bithiophen-5-yl) substituted 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole.

A new synthetic approach towards the preparation of functionalised, soluble, donor-acceptor (DA) alkylbithiophene derivatives of oxadiazole, thiadiazole and triazole is reported. Taking advantage of the Fiesselmann reaction, reactive bithiophene synthons having alkyl or alkoxy substituents at designated positions are prepared. Following a synthetic strategy, featuring the bottom-up approach, sequential structural elements are built, starting from a simple thiophene compound, until the target molecule is obtained, all in good yield.

A simple and efficient synthesis of substituted 2,2'-bithiophene and 2,2':5',2″-terthiophene.

A simple and efficient approach is developed for the synthesis of substituted 2,2'-bithiophene- and 2,2':5',2″-terthiophene-5-carboxylic acids and esters which is based on thiophene ring closure in the Fiesselmann reaction. Using this method, derivatives containing a long alkyl chain with or without an end functional group or an aryl substituent can be conveniently prepared.