Hydrogels of carboxymethylcellulose (CMC) with 2.5%, 25%, 50%, and 100% cross-linking were prepared. Cross-linking and stoichiometry was controlled by appropriate addition of CMPJ and determined by potentiometric titration. The cross-linked polymer was then sulfated using a sulfur trioxidepyridine complex (SO 3-Py) in a heterogeneous mixture. Water uptake of the gels was studied in relation to cross-linking, pH, and sulfation. FT-IR spectra of the gels were recorded at different pHs to evidence the hydrogen bonds. Hydrogen bonds formation between the chains may explain the correlation found between water uptake properties and the chemical composition of the gels.

Successful attempts to deposit SMMs in UHV conditions\ud have been carried out with a tetranuclear iron(III) cluster [ 9 ]\ud and lanthanide bis-phthalocyaninato (LnPc 2 ) complexes. [ 10 , 11 ]\ud For the latter the seminal works of Ishikawa et al. [ 12 ] showed\ud that slow dynamics of the magnetization in these mononuclear\ud complexes is originated directly from their strong single ion\ud anisotropy. Very recently a structural and magnetic characterization\ud of a sub-monolayer deposit TbPc 2 based on synchrotronlight\ud techniques has confi rmed that this magnetic anisotropy is\ud retained on surface. [ 13 ] The absence of the observation of typical\ud slow dynamics of the magnetization has been attributed to the\ud long time-scale of the X-ray based experiments.\ud We report here a synchrotron-based investigation on neutral\ud TbPc 2 evaporated thick and thin fi lms evidencing that the thick\ud fi lm of TbPc 2 is characterized by slow relaxation of the magnetization\ud and opening of a butterfl y hysteresis cycle at temperatures\ud as high as 15 K but not observed for the thin fi lm. These\ud differences are accompanied with a drastic change in the orientation\ud of the TbPc 2 molecules in the two fi lm

Electron spin resonance (ESR), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and scanning tunneling microscopy (STM) have been used in parallel to characterize the deposition on gold surface of a series of nitronyl nitroxide radicals. These compounds have been specifically synthesized with methyl-thio linking groups suitable to interact with the gold surface to form self-assembled monolayers (SAMs), which can be considered relevant in the research for molecular-based spintronics devices, as suggested in recent papers. The degree of the expected ordering on the surface of these SAMs has been tuned by varying the chemical structure of synthesized radicals. ToF-SIMS has been used to support the evidence of the occurrence of the deposition process. STM has shown the different qualities of the obtained SAMs, with the degree of local order increasing as the degree of freedom of the molecules on the surface is decreased. Finally, ESR has confirmed that the deposition process does not affect the paramagnetic characteristics of radicals and that it affords a complete single-layered coverage of the surface. Further, the absence of angular dependence in the spectra indicates that the small regions of local ordering do not give rise to a long-range order and suggests a quite large mobility of the radical on the surface, probably due to the weak interaction with gold provided by the methyl-thio linking group.