Phenyl-substituted planar binuclear phthalo- and naphthalocyanines: synthesis and investigation of physicochemical properties Tatiana V. Dubinina a, b, * , Stanislav A. Trashin b,1 , Natalia E. Borisova a , Irina A. Boginskaya c , Larisa G. Tomilova a, b, 1 , Nikolay S. Zefirov a a Chemistry Department, M.V. Lomonosov Moscow State University, 1 Leninskie Gory, 119991 Moscow, Russian Federation b Institute of Physiologically Active Compounds, Russian Academy of Sciences, 1 Severny proezd, 142432 Chernogolovka, Moscow Region, Russian Federation c Institute for Theoretical and Applied Electromagnetics, Russian Academy of Sciences, 125412, 13 Izhorskaya St., Moscow, Russian Federation article info Article history: Received 30 August 2011 Received in revised form 17 October 2011 Accepted 18 October 2011 Available online 2 November 2011 Keywords: Naphthalocyanines NIR absorption Electrochemistry Nanoparticles Pi interactions Binuclear phthalocyanines abstract Dodeca-phenyl-substituted planar binuclear phthalocyanine magnesium complexes with an extended p-conjugation system were synthesized with high yields. Two approaches to the extension of the p- system were presented: extension of an aromatic bridge or a peripheral p-system. A maximum of near-IR absorption at 972 nm was observed in the case of the planar binuclear naphthalocyanine sharing a common benzene ring. Binuclear phthalo- and naphthalocyanines were characterized by high reso- lution MALDI-TOF mass spectrometry, UV/Vis/NIR and 1 H NMR spectroscopy. DFT modeling of the structure and chemical shift GIAO calculations were made. The formation of nanoaggregates in a solid film was proven using AFM. The electrochemical properties of binuclear naphthalocyanine complexes were investigated for the first time. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Phthalocyanines with an extended p-conjugation system are of increasing importance due to the presence of absorption in the near- IR region. This peculiarity allows for the use of planar binuclear phthalocyanines as components of photogalvanic cells [1], optical electronic devices for the near-IR region [2], photooxidative catalysis [3] and laser assisted processes [4]. The phthalo- and naph- thalocyanines possessing narrow absorption in the near-IR region have been well-studied [5e9]. However, the absorption maximum of these compounds is often too sharp and does not coincide well with the wavelengths of laser light [4]. Planar binuclear phthalocyanines have potential for this application since some electron transitions corresponding to Q-bands occupy a wide region of wavelengths in the near-IR region [4,10e13]. Moreover, the Q-band position can be controlled using the extension of the p-system. The extension of the p-system of planar binuclear phthalocya- nines can be performed in two ways: extension of an aromatic bridge or a peripheral p-system. Attempts at aromatic bridge extension from benzene to naphthalene [14e16] and tetracene [17] have been described in the literature. For these binuclear species, absorption in the near-IR region was not found. However, in our previous work, [11] it was shown that the extension of an aromatic bridge leads not to the disappearance of but to the hypsochromic shift of the Q-band. In order to expand the peripheral p-system, an asymmetrical binuclear compound containing phthalocyanine and naph- thalocyanine moieties was obtained [4,18]. Synthetic approaches to symmetrical binuclear naphthalocyanine complexes have been recently described [12,19]. The highest value of bathochromic shift of the Q-band was reached by us in the case of dodeca-substituted planar binuclear naphthalocyanine sharing a common benzene ring [19]. Because of the different substituents and central ions, which include considerable contributions to spectral properties, the literature data on planar binuclear phthalocyanines were difficult to systematize. Moreover, electrochemical investigations on planar binuclear naphthalocyanines have not been carried out. The main purpose of this work was to determine the correlation between the extension of the aromatic system and the position of * Corresponding author. Chemistry Department, M.V. Lomonosov Moscow State University,1 Leninskie Gory,119991 Moscow, Russian Federation. Fax: þ7 (495) 939 0290. E-mail addresses: dubinina.t.vid@gmail.com (T.V. Dubinina), tom@org.chem. msu.ru (L.G. Tomilova). 1 Fax: þ7 496 524 9508. Contents lists available at SciVerse ScienceDirect Dyes and Pigments journal homepage: www.elsevier.com/locate/dyepig 0143-7208/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.dyepig.2011.10.012 Dyes and Pigments 93 (2012) 1471e1480