Electronic, molecular, and solid-state structural effects of strong electron withdrawing and donating groups in functionalized fluorophthalonitriles

Abstract

Perfluoro phthalonitrile substituted separately with perfluoroalkyl (EWG) and NH2, NHMe, and NMe2 (EDG) groups generate a series of aromatic C-H bonds-free nitriles that can now lose electrons, whose HOMO–LUMO gap is narrowed by EDG beyond the level induced by EWG, and whose dipole moments double. Molecular parameters vary linearly with Hammett’s free-energy constants, their electronic underpinning being uncovered by DFT calculations. The phthalonitriles’ assembling in solid-state structures is determined by forces that transition from van der Waals, in the case of EWG, to H-bonding and/or [Formula: see text]-stacking interactions in the case of EDG, as revealed by their single-crystal X-ray structures.

Development of 19F‐detected 1,1‐ADEQUATE for the characterization of polyfluorinated and perfluorinated compounds

“…The black curve is a 50 Hz compromise optimization that would typically be employed using survey conditions for 1 H-detected 1,1-ADEQUATE experiment being performed on an aralkyl compound. [42][43][44][45][46] As is readily discerned from these data, although all of the correlations reflected by the 1 J CC coupling constants of 1 would give high and usable intensity, only the correlation for the coupling constant between C3 and C4 (69.1 Hz, Table 2) would afford peak intensity (black curve) near 0.7, whereas the remainder of the correlations were <0.4 in intensity. As would be expected, the observed 2 J CC correlation, e.g.…”

“…The N,N-dimethylamino-2,3,6-trifluorophthalonitrile, 1, was synthesized using the procedure reported by Pelmus et al, [46] which was a modified procedure from Tanabe and Ishikawa. [48] All NMR experiments were performed on a JEOL ECZ500R spectrometer equipped with a 5-mm SuperCOOL™ liquid nitrogen-cooled Royal cryoprobe, operating at a 1 H observation frequency of 500.16 MHz.…”

“…To underscore the importance of properly optimizing the delays based on the 1 J CC coupling constant in the 19 F-detected 1,1-ADEQUATE experiment, the measured 1 J CC coupling constants (see Table 2) were plotted on the calculated amplitude transfer curves for 80 and 50 Hz optimization of the 1,1-ADEQUATE experiment in Figure 9. The 80 Hz optimization was chosen based on the measured 1 J CC coupling constants from this study, whereas the 50 Hz optimization represents the typical compromise [42][43][44][45][46] that would typically be employed for a 1 H-detected 1,1-ADEQUATE experiment performed on an aralkyl compound. We are working to further refine the 19 F-detected 1,1-ADEQUATE experiment to make it more robust and to hopefully improve the sensitivity of the experiment.…”

J‐modulated 19F‐ and 1H‐detected dual‐optimized inverted 1JCC 1,n‐ADEQUATE: A universal ADEQUATE experiment

“…All NMR data were acquired using either a 53‐mg sample of N,N ‐dimethylamino‐2,5,6‐trifluoro‐3,4‐phthalonitrile ( 1 ) [ 33 ] or a 50‐mg sample of N,N ‐dimethylamino‐3,4‐phthalonitrile ( 2 ) [ 34 ] dissolved in 550 μl of DMSO‐ d 6 . [ 1 ] Concentrated samples were employed to facilitate data analysis and the generation of publication quality data; less concentrated samples can be employed for routine analysis.…”