Spectroscopic characterization of C-4 substituted 3,5-dichloro-4H-1,2,6-thiadiazinesElectronic supplementary information (ESI) available: Comparison of IR and resonance Raman spectra of thiadiazines 5a-c (Fig. S1). Atomic coordinates of the geometry-optimized structures of thiadiazines 5a-c and their H analogues using MP2/6-311G(d). Comparison of bond lengths and angles of thiadiazines 5a-c from single crystal X-ray structures and geometry optimizations. CCDC 1038262. For ESI and crystallographi

• Main Authors: Theodorou, Eleni, Ioannidou, Heraklidia A, Ioannou, Theodosia A, Kalogirou, Andreas S, Constantinides, Christos P, Manoli, Maria, Koutentis, Panayiotis A, Hayes, Sophia C
• Format: Article
• Language: English
• ISSN: 2046-2069
• DOI: 10.1039/c4ra16144k

Three 3,5-dichloro-4 H -1,2,6-thiadiazines, which differ according to the electron withdrawing nature of their substituent at C-4: (a) 3,5-dichloro-4-methylene-4 H -1,2,6-thiadiazine ( 5a ), (b) 3,5-dichloro-4 H -1,2,6-thiadiazin-4-one ( 5b ) and (c) 2-(3,5-dichloro-4 H -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-4 H -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. The effect of C-4 substitution with electron withdrawing groups on the structure and electronic properties of three 3,5-dichloro-4 H -1,2,6-thiadiazines is characterized using resonance Raman, absorption and photoluminescence spectroscopies.