Nucleophilic substitution reactions of phenolphthalein with different substituted cyclotriphosphazene derivatives Gönül Yenilmez Çiftçi ⇑ , Elif S ßenkuytu, Mahmut Durmus ß, Adem Kılıç Gebze Institute of Technology, Department of Chemistry, Gebze 41400, Kocaeli, Turkey article info Article history: Received 18 April 2013 Accepted 3 July 2013 Available online 12 July 2013 Keywords: Phosphazenes Cyclotriphosphazenes Phenolphthalein Fluorescence NMR abstract In the present work, the partially or fully substituted phenolphthalein bridged cyclotriphosphazene derivatives and their spectral properties were reported for the first time. The reactions of phenolphtha- lein (2), with racemic trans-2,4-bis(dibenzylamino)-2,4,6,6-tetrachlorocyclotriphosphazene (3), 2,2,4,4- tetra(anilino)-6,6-dichlorocyclotriphosphazene (4), 2,2,4,4-tetrathiophenoxy-6,6-dichlorocyclotriphos- phazene (5) and 2,2,4,4,6-pentaphenoxy-6-chlorocyclotriphosphazene (6) in THF gave phenolphthalein bridged cyclotriphosphazene compounds 7–10. All these compounds (7–10) were fully characterized by elemental analysis, FT-IR, mass (MS), 1 H, 13 C and 31 P NMR, electronic absorption and fluorescence spectroscopies. The fluorescence properties of novel phenolphthalein bridged dibenzylamino, anilino, thiophenoxy and phenoxy substituted cyclotriphosphazene compounds (7–10) were investigated and compared in dichloromethane. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Phosphazenes are important family of inorganic systems consist of the repeating units – [N@PR 2 ] – with trivalent nitrogen and pen- tavalent phosphorus atoms. They can be represented in the form of linear short-chain, cyclic, or high-molecular-weight polymers. When the side group ‘‘R’’ is a halogen, it can be replaced with ami- no, thiol, aliphatic or aromatic alcohol groups via nucleophilic sub- stitution reactions thus forming phosphazene compounds bearing different properties [1–7]. Hexachlorocyclotriphosphazene, N 3 P 3 Cl 6 , 1, which is one of these compounds particularly attracts attention as this inorganic core can be easily functionalized on the phosphorus atoms, thus giving rise to a wide variety of branched molecules [8–12]. As a result of substitution reactions of the reactive P–Cl bonds on the phosphazene group, novel cyclo- triphosphazene compounds exhibit several applications. Cyclotri- phosphazenes could form a core to synthesize a variety of compounds that can be utilized used as biomedical materials, anti- cancer and antimicrobial agents [13–17], liquid crystals [18,19] and organic light emitting diodes [20]. Generally, the reaction of N 3 P 3 Cl 6 with monofunctional re- agents could follow geminal or nongeminal replacement pattern or mixture of both. The nongeminal mode permits the possibility of cis–trans isomerism. This type of isomerism depends on the dis- position of groups with respect to the plane of the ring. In most reactions, both types of replacements occur although usually one of them predominates. The reaction of N 3 P 3 Cl 6 with thiolate groups (e.g., thiophenol) and primary amine (e.g., t-butylamine, aniline) gives geminal products almost exclusively, this situation proceed successively via SN 1 (P) mechanism [21,22]. Additionally, second- ary amines such as dimethylamine or dibenzylamine react pre- dominantly by the nongeminal mode of the replacement and this observation is consistent with SN 2 (P) mechanism [23]. Steric ef- fects obviously play an important role in the reaction of dibenzyl- amine with compound 1. The reaction of these two compounds yielded two products, the mono-, N 3 P 3 Cl 5 [N(CH 2 Ph) 2 ], and bis dib- enzylamino derivative, N 3 P 3 Cl 4 [N(CH 2 Ph) 2 ] 2 , the latter suggested to be trans-nongeminal form [24]. On the other hand, stoichiome- tric reaction of N 3 P 3 Cl 6 with phenols can afford various products including N 3 P 3 Cl 5 (OPh), cis-nongeminal N 3 P 3 (OPh) 4 Cl 2 , and N 3 P 3 (OPh) 5 Cl [25]. In addition, reactions of compound 1 with difunctional reagents may lead to different types of products that have a variety of struc- tures such as open chained, bridged, spiro, ansa, oligomer or poly- mer and their mixtures. The parameters can affect the formation of these products include the chain length of the difunctional reagents, solvent, base, temperature, the nature of the reacting functional groups and the size of the cyclotriphosphazene ring [11,26–30]. Most of bridged cyclotriphosphazene compounds are based on linking two cyclotriphosphazene derivatives with linear primary diamines, polyamines with secondary diamines and di- alcohols [31–32]. Bridged cyclotriphosphazene compounds which obtain the reaction of 1 with diol groups containing different length chains are important. This reactions may result in bridge and ansa compounds when the chain lengths n > 5, n = 5–10 on 0277-5387/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.poly.2013.07.006 ⇑ Corresponding author. Tel.: +90 262 605 3071; fax: +90 262 605 3101. E-mail address: yenilmez@gyte.edu.tr (G.Y. Çiftçi). Polyhedron 63 (2013) 60–67 Contents lists available at SciVerse ScienceDirect Polyhedron journal homepage: www.elsevier.com/locate/poly