Electronic Supporting Information

General: all reagents were purchased from commercial sources and used without further purification. Column chromatography was performed with silica gel 60 (Merck 9385, 230–400 mesh) or aluminium oxide 90 (neutral, act. II–III, Merck 1097). NMR experimental : NMR spectra were acquired on a Bruker Avance-300 apparatus operating at 300.33 MHz for H and 75.52 MHz for C, equipped with a standard 4 mm H/X probe, with rotor spinning at 10 kHz. H MAS spectra were acquired with 8 scans and 10 s as repetition delay. C CPMAS acquisitions lasted 12 hours on average and involved a contact time equal to 2.5 ms, 5 s as repetition delay, 53 kHz and 63 kHz as H and C RF frequencies respectively and spinal64 composite pulse decoupling with 90 kHz H RF frequency. A Bruker Avance-300 spectrometer was used for solution NMR analysis. TGA and DSC experimental: TGA and DSC measurements were performed respectively on a Pyris 6 TGA (PerkinElmer) and a Jade DSC (PerkinElmer) apparatus . Mass spectra were obtained with a VG-BIOQ triple quadrupole in positive mode (ESMS). Microanalyses were performed by the Service de Microanalyses de la Fédération de Recherche de Chimie, Université de Strasbourg, Strasbourg. Data were collected at 173(2) K on a Bruker APEX8 CCD Diffractometer equipped with an Oxford Cryosystem liquid N2 device, using graphite-monochromated Mo K (= 0.71073) radiation. The structures were solved using SHELXS-97 and refined by full matrix least-squares on F2 using SHELXL-97.21 The hydrogen atoms were introduced at calculated positions and not refined (riding model).