A theoretical and experimental exploration of the mechanism of microwave assisted 1,3-dipolar cycloaddition of pyridinium ylides to single walled carbon nanotubes

Sensing properties of light-emitting single walled carbon nanotubes prepared via click chemistry of ylides bound to the nanotube surface

“…The pyridinium ylide, rather than reacting with the CNT surface directly, is covalently bonded to the nanotube which then undergoes 1, 3-dipolar cycloaddition with dimethyl acetylenedicarboxylate (DMAD) to yield uorescent indolizines, Scheme 1. In contrast to previously reported method, 21,23 combined diazonium salt-click chemistry approach described here offers high yielding indolizine formations at low temperatures, more control on reaction conditions, possible choice of dipoles/dipolarophiles with desired side groups (e.g. cyclodextrins, 40 activated alkynes or alkenes at low temperatures 41 ) and the characterization of reaction intermediates.…”

“…The deconvoluted N 1s XPS spectrum of 1a showed three peaks that can be probably attributed to the quaternary nitrogen (N + ) at ca. 402.3 eV, 23,46 pyridinic nitrogen at 398.9 eV (ref. 21, 23 and 35) and pyridine radical cation (N + c) at 400.2 eV.…”

“…399.9 and 398.9 eV and a new peak generated at 401.4 eV that probably correspond to indolizine ring nitrogen (-N<). 49 The deconvoluted N 1s XPS spectrum of 3a showed signature of nitro group (-NO 2 ), 23 pyridine diazo (-N]N), 50 quaternary nitrogen (N + ) 23 and pyridine radical cation (N + c) 47,48 at ca. 406.2, 403.8, 402.4 and 400.1, respectively.…”

“…XPS was used to conrm the reduction of nitro (NO 2 ) groups into amines (NH 2 ). N 1s XPS spectrum of 3c showed three components positioned at 406.4, 401.0 and 399.2 eV, corresponding to nitro groups (-NO 2 ), 23 the indolizine ring nitrogen (-N<) 49 and pyridinic nitrogen, 35 respectively (see ESI Fig. S2 †).…”

“…17 Introducing surface groups also enhanced the processability of CNTs, particularly SWCNTs, in both aqueous and nonaqueous solvents by interrupting the strong van der Waals forces causing aggregation or bundling of the material. Covalent strategies to functionalize SWCNTs have included carbene, 18 radical, 19,20 cycloaddition, [21][22][23][24] organolithium addition 25,26 and oxidation 27,28 reactions and been recently reviewed. 29 Among radical reactions aryl diazonium salts addition 19,[30][31][32][33][34] has widely been studied using diazonium salts directly 30 or generating them in situ by oxidation of the corresponding aniline with inorganic 31 or organic 32 oxidants.…”