Variable-temperature (VT) solid-state 19 F NMR spectroscopy with high-speed magic-angle spinning (MAS) has been used to study copolymers of vinylidene fluoride and hexafluoropropylene and of vinylidene fluoride and chlorotrifluoroethylene, and terpolymers of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene. High-resolution spectra were obtained by simultaneously using MAS speeds up to 25 kHz and heating to 250°C. Sufficient resolution was achieved to assign peaks by comparison to results obtained from solution-state NMR studies and to determine the monomer composition of the polymer.

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a metabolite of NADP with Ca2+ mobilizing activity. The Ca2+ release mechanism activated by NAADP as well as the Ca2+ stores that it acts on are different from those activated by either cyclic ADP-ribose or inositol 1,4,5-trisphosphate (IP3) (Lee, H. C., and Aarhus, R. (1995) J. Biol. Chem. 270, 2152-2157). In order to demonstrate unambiguously that NAADP can mobilize Ca2+ stores in live cells, a caged analog was synthesized by reacting NAADP with 1-(2-nitrophenyl)diazoethane. Anion exchange high pressure liquid chromatography (HPLC) was used to purify one particular caged form from the mixture of products. Phosphate analyses following specific enzymatic cleavage indicate that the caging group is on the 2'-phosphate. This is confirmed by 31P NMR spectroscopy, showing that the 2'-phosphate of the caged compound exhibits an altered chemical shift of -2.6 ppm as compared with 2.3 ppm determined for the 2'-phosphate of NAADP. Caged NAADP had no Ca2+ releasing activity at a concentration as high as 1 micro;M when tested on sea urchin egg microsomes. After photolysis, it released Ca2+, was effective in nanomolar range, and was indistinguishable from authentic NAADP. The regeneration of NAADP after photolysis was also confirmed by HPLC analyses. The analog is particularly susceptible to UV and can be efficiently photolyzed using a spectrofluorimeter. To demonstrate its utility in live cells, caged NAADP was microinjected into sea urchin eggs. Photolysis effectively regenerated NAADP and activated Ca2+ oscillations in the eggs. Removal of external Ca2+ did not prevent the Ca2+ oscillations but only delayed the second Ca2+ peak by about 45 s, indicating that the oscillations are due to release from internal stores and not caused by Ca2+ influx. A mechanism based on sensitization of the Ca2+ release by Ca2+ loading is proposed to account for the Ca2+ oscillation observed.

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A new class of ionic photo-acid generators (PAGs) useful in chemically amplified photoresist formulations has been developed. The new PAGs are salts comprising a photoactive cation and a fluoroorganic sulfonylimide or sulfonylmethide anion. These highly delocalized, nitrogen-and carbon-centered anions are extremely nonbasic and weakly coordinating. Correspondingly, their conjugate acids are powerful superacids. The imide and methide acids produced by photolysis of the corresponding ionic PAGs are highly active in initiating the cationic polymerization of various organic monomers (as in negative resists) and have been shown to catalyze the deprotection of acid-sensitive organic functional groups (as in high activation energy, positive resists) with good photospeeds. The unique balance of reactivity and physical properties provided by the imide and methide anions suggests that they may be useful alternatives to, or replacements for, the organic or inorganic anions commonly employed in existing ionic PAG formulations (e.g., perfluoroalkanesulfonate anions and MF 6 -anions, where M is Sb, As or P). A family of ionic PAGs based upon these new anions and their combinations with diaryliodonium or triarylsulfonium cations has recently been made available by 3M as experimental products for lithographic evaluations in positive and negative photoresists. In this report we will describe the characterization of these PAGs, including melting points, thermal stabilities, UV extinction coefficients, solubilities and photo-acid volatilities. Potential advantages of these new PAGs in positive and negative photoresist applications will also be presented.