Quantifying Intrinsic Ion-Driven Conformational Changes in Diphenylacetylene Supramolecular Switches with Cryogenic Ion Vibrational Spectroscopy

Abstract

We report how two flexible diphenylacetylene (DPA) derivatives distort to accommodate both cationic and anionic partners in the binary X(±)·DPA series with X = TMA(+) (tetramethylammonium), Na(+), Cl(-), Br(-), and I(-). This is accomplished through theoretical analysis of X(±)·DPA·2D2 vibrational spectra, acquired by predissociation of the weakly bound D2 adducts formed in a 10 K ion trap. DPA binds the weakly coordinating TMA(+) ion with an arrangement similar to that of the neutral compound, whereas the smaller Na(+) ion breaks all intramolecular H-bonds yielding a structure akin to the transition state for interconversion of the two conformations in neutral DPA. Halides coordinate to the urea NH donors in a bidentate H-bonded configuration analogous to the single intramolecular H-bonded motif identified at high chloride concentrations in solution. Three positions of the "switch" are thus identified in the intrinsic ion accommodation profile that differ by the number of intramolecular H-bonds (0, 1, or 2) at play.

Guest dependent dielectric properties of nickel(ii)-based supramolecular networks

“…Self-assembly processes involving metal ions and well-designed organic ligands give rise to interesting functional hybrid materials. Recently, supramolecular networks and coordination polymers have found wide applications due to their versatile properties such as their ability to function as molecular sensors, [1][2][3][4][5] molecular switches, [6][7][8][9] catalysts, [10][11][12][13] self-healing polymers, [14][15][16][17] synthetic ion channels [18][19][20][21] and in the treatment of radioactive waste. 22,23 However, reports concerning the dielectric properties of these materials are sparse even though they possess advantageous properties of functioning as both inorganic and organic compounds.…”

Intramolecular Hydrogen Bonding Motifs in Deprotonated Glycine Peptides by Cryogenic Ion Infrared Spectroscopy

“…This is approximately the expected shift induced by a neutral hydrogen bond. 41,42 However, it is unexpected in this case given that the difference in energy between the conformers in Figure 3B,C indicates that this H-bonding interaction is only about 200 cm −1 . Furthermore, even though the α-CO is free in (G 3 − H) − and (G 4 −H) − , its frequency is still anomalously red-shifted by about 20 cm −1 .…”

Ion and Molecular Recognition Using Aryl–Ethynyl Scaffolding

“…A new Na + complex has been observed by cryogenic ion vibrational predissociation spectroscopy that is analogous to the rotational transition state between the two ‘closed’ states. [68] The ‘open’ state can also be considered similar to the unbound state of an alkyne anion host that lacks preorganization.…”