The preparation of 3,6‐bis(3‐hexylthien‐2‐yl)‐s‐tetrazine and its conjugated polymers

Abstract

We demonstrated, for the first time, that 3,6‐bis(3‐hexylthien‐2‐yl)‐s‐tetrazine (TTz) with hexyl group at the 3‐position of thiophene rings can be prepared using a modified sulfur‐assisted Pinner synthesis. Although the hexyl group creates large steric hindrance to the tetrazine ring formation reaction, and the reaction under a traditional condition only produces trace amount of the target product, the yield of this reaction under a modified reaction condition using anhydrous hydrazine at 68 °C can reach 65%. Two new copolymers of the resulting TTz and hexyl‐ or 2‐ethylhexyl‐substituted cyclepentadithiophene have been prepared. The polymers show a broader light absorption in film than in solution attributing to the large distribution of effective conjugation length of polymer chain due to the existence of both cis‐ and trans‐orientations of the 3‐hexylthiophene units in the planar polymer chain in solid state. Although the polymers show a narrow band gap and a deep HOMO level, which are desirable for generating an efficient light absorption and a larger open circuit voltage (Voc) of the resulting solar cell devices, the device performance is not as good as expected. It is attributed to the random distribution of the cis‐ and trans‐conformations along the polymer chain. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.

Inverse electron demand Diels–Alder reactions in chemical biology

“…75,76 Sulphur is described to react first with hydrazine to give NH 2 NHSH, which serves as an active nucleophile towards nitriles, generating a reactive intermediate that eliminates H 2 S to form the dihydrotetrazine core. 43,75,77 Importantly, although these conditions have been successfully used for the synthesis of aromatic tetrazines, very low yields are reported in the case of alkyl tetrazines. Alternatively, N-acetylcysteine was successfully tested as catalyst for the synthesis of tetrazines possibly through the formation of amidrazone intermediates.…”

Structures and properties of conjugated Donor–Acceptor copolymers for solar cell applications

“…Acceptor unit refers to electron-deficient (or electron-poor) groups, almost each acceptor unit contains the electron-withdrawing imine (-C]N) nitrogen (such as benzothiadiazole (BT), [47][48][49] quinoxaline (QA), 50,51 thienopyrazine (TP), [52][53][54] bithiazole (BTz), [55][56][57][58][59][60] thiazolothiazole (TTz), 43,61-66 benzobisthiazole (BBTz), 20,67 benzotriazole (BTA), [68][69][70][71] s-tetrazine (STTz), 72,73 naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole (NT) 74 or carbonyl groups (C]O) (such as diketopyrrolopyrrole (DPP), 75,76 [2,3-c]thiophene-4,9-dione (NTDO), 77,78 isoindigo (II), [79][80][81] and thieno[3,4-c]pyrrole-4,6-dione (TPD) [82][83][84][85][86][87] ). The chemical structures of these acceptor units are shown in Fig.…”

Structural Engineering in Polymer Semiconductors with Aromatic N-Heterocycles

“…Diheteroaryl s -tetrazine is readily available by treatment of heteroaryl nitrile with hydrazine hydrate and subsequent oxidation. This class of molecules was applicable to polymeric photovoltaics in the early 2010s. − Owing to the high electron deficiency of s -tetrazine, this structure is very compatible with conventional electron acceptors, such as naphthalene diimide, to construct n-type semiconductors. For example, dithienyl s -tetrazine bridges two naphthalene diimide terminals to forge an acceptor triad.…”