Acid/base controllable molecular switch based on a neutral phenanthroline guest penetrated pseudorotaxane

Abstract

A ditopic macrocycle with a bisamide and a half dibenzo-crown ether component has been newly synthesized and its complexation behavior toward neutral phenanthroline derivatives is reported. The macrocycle can bind phenanthroline derivatives very strongly by hydrogen bonding and pi-electron interaction, yielding pseudorotaxane structures. The inclusion complexes show a pH controllable reversible threading-dethreading molecular switching system.

Conformational Switching of Multi‐Responsive Ferrocenyl‐Phenol Conjugates

“…Several elegant studies have been devoted to structural rearrangements and molecular recognition events in the fields of rotaxanes, [1][2][3][4][5][6] calixarenes, [7] porphyrins, [8] phenol/phenolate conjugate acid/base pairs, [9,10] spiro-oxazines, [11] and many other structures. Several elegant studies have been devoted to structural rearrangements and molecular recognition events in the fields of rotaxanes, [1][2][3][4][5][6] calixarenes, [7] porphyrins, [8] phenol/phenolate conjugate acid/base pairs, [9,10] spiro-oxazines, [11] and many other structures.…”

“…Conformational changes triggered by chemical stimuli, such as acids or bases (acid/base switches), are a viable tool for tuning molecular properties and geometrical architectures to achieve molecular-sized devices. Several elegant studies have been devoted to structural rearrangements and molecular recognition events in the fields of rotaxanes, [1][2][3][4][5][6] calixarenes, [7] porphyrins, [8] phenol/phenolate conjugate acid/base pairs, [9,10] spiro-oxazines, [11] and many other structures. [12] We have been investigating the secondary structure as well as the proton-and electron-transfer-initiated rearrangements of a ferrocenyl-phenol conjugate H-A OO featuring a ferrocenyl moiety and a salicylic acid amide residue (Scheme 1, a).…”

Template-Free Synthesis of a Phenanthroline-Containing [2]Rotaxane: A Reversible pH-Controllable Molecular Switch

“…As shown in Scheme 2, we previously demonstrated by 1 H NMR spectral changes and 1 H NMR spectroscopic titration experiments that macrocycle 1 very strongly binds 2,9-dimethyl-1,10-phenanthroline (DMPhen) [22].…”

“…As shown in Scheme 2, we previously demonstrated by 1 H NMR spectral changes and 1 H NMR spectroscopic titration experiments that macrocycle 1 very strongly binds 2,9-dimethyl-1,10phenanthroline (DMPhen) [22]. We expected that the corresponding [2]pseudorotaxane structures would be formed by stabilization from the cooperative effects of NH-N hydrogen bonding between the isophthalamide protons and the DMPhen nitrogen atoms, as well as by π-stacking of the two πelectron-rich aromatic rings of macrocycle 1 with the π-electron-deficient aromatic ring of the neutral phenanthroline derivative in CDCl3.…”

“…All reagents were obtained from commercial suppliers (tritylaniline; Alfa Aesar by Thermo Fisher Scientific, Heysham, Lancasshire, U.K., sodium triacetoxyborohydride; Tokyo Chemical Industry Co., Ltd., Tokyo, Japan, other reagents and solvents; FUJIFILM Wako Pure Chemical Co., Osaka, Japan) and used as received. Macrocycle 1 [22] and thread precursor 2 [23] were synthesized according to literature procedures. 1 H and 13 C NMR spectra were recorded with a Varian Mercury 300 spectrometer (Agilent Technologies Japan, Ltd., Tokyo, Japan) for solution in CDCl 3 with SiMe 4 as an internal standard.…”