Tetrabenzylcyclen as a receptor for fluoride

Abstract

A tetraazacyclic ligand, tetrabenzylcyclen (L), was synthesized using an improved method with a higher yield by treatment of cyclen with benzylchloride in the presence of potassium carbonate. The reaction of L with an aqueous solution of fluorosilicic acid yielded a mixed-anionic salt with the composition [H 3 L][F][SiF 6 ]$4H 2 O (1). The single crystal X-ray study revealed that the macrocyclic trication essentially changes the conformation compared to the free ligand in order to tightly accommodate the fluoride inside and to keep the hexafluorosilicate anions and water molecules outside in the solid state complex.

From Cyclic Peptoids to Peraza-macrocycles: A General Reductive Approach

“…Four nitrogen atoms are coordinated to the cation (Na−N distances within 2.45−2.55 Å), and two opposite η 3 benzyl moieties complete the first coordination sphere (Na−C distances within 2.99−3.32 Å). The macrocycle conformation in [26•Na] + TFPB − is different from that evident in the free ligand 21 and similar to that observed by Habata and co-workers in argentivorous complexes. 17a NMR titration by stepwise quantitative additions of sodium tetrakis [3,5-bis(trifluoromethyl)phenyl]borate (NaTFPB) to CDCl 3 solutions of cyclotetramer 26 showed the formation of a metalated species (see Figure S1) displaying an upfield shift of the benzyl ortho-protons (from 7.30 to 6.04 ppm) similar to that observed by Habata in the presence of Ag +ion.…”

“…Four nitrogen atoms are coordinated to the cation (Na–N distances within 2.45–2.55 Å), and two opposite η 3 benzyl moieties complete the first coordination sphere (Na–C distances within 2.99–3.32 Å). The macrocycle conformation in [ 26 ·Na] + TFPB – is different from that evident in the free ligand and similar to that observed by Habata and co-workers in argentivorous complexes…”

Exciplex Formation and Aggregation Induced Emission in Di‐(N‐benzyl)cyclen and Its Complexes – Selective Fluorescence with Lead(II), and as the Cadmium(II) Complex, with the Chloride Ion

“…This was our first thought on the origin of the slow appearance of the peak, so that an investigation of the conformers of protonated and neutral forms of DB cyclen was carried out by DFT calculation. By comparison with the known structures of the neutral and protonated forms of TB‐cyclen, and a DFT based investigation, the conformers in Figure were identified as probably being of the lowest energy for the neutral and deprotonated forms of DB‐cyclen.…”