Octopus‐Type Crown‐Bisphthalocyaninate Anchor for Bottom‐Up Assembly of Supramolecular Bilayers with Expanded Redox‐Switching Capability

Abstract

Achievement of information storage at molecular level remains a pressing task in miniaturization of computing technology. One of the promising approaches for its practical realization is development of nanoscale molecular switching materials including redox‐active systems. The present work demonstrates a concept of expansion of a number of available redox‐states of self‐assembled monolayers through supramolecular approach. For this, the authors synthesized an octopus‐like heteroleptic terbium(III) bisphthalocyaninate bearing one ligand with eight thioacetate‐terminated “tentacles” (octopus‐Pc) and a ligand with four crown‐ether moieties (H2[(15C5)4Pc]). It is shown that octopus‐Pc forms stable monolayers on gold, where its face‐on orientation allows for subsequent binding of crown‐phthalocyanine molecules via potassium ion bridges. This chemistry is utilized to form a heterogeneous bilayer, in which a single molecule thick adlayer brings an additional redox‐state to the system, thus expanding the multistability of the system as a whole. All four redox states available to this system exhibit characteristic absorbance in visible range, allowing for the switching to be easily read out using optical density measurements. The proposed approach can be used in wide range of switchable materials—single‐molecule magnets, conductive, and optical devices, etc.

Rare-earth based tetrapyrrolic sandwiches: chemistry, materials and applications

“…66 A heteroleptic octopus-type Tb(III) bisphthalocyaninate bearing a 15-crown-substituted ligand and a ligand with eight thioacetate-terminated flexible tentacles was synthesized by Shokurov et al via the raise-by-one-story approach starting from tetrahydropyranyl-protected phthalocyanine and halfsandwich Tb(III) crown-phthalocyaninate followed by the cleavage of protective groups, the introduction of iodine atoms and their nucleophilic substitution with thioacetate residues (Scheme 4). 73 The resulting octopus formed a self-assembled monolayer (SAM) on gold with a face-to-face orientation of the molecules, serving as an anchor for further surface modification, namely the binding of additional crown phthalocyanine molecules via potassium ion bridges. The enhanced redoxswitching ability of the bilayer thus formed was demonstrated (cf.…”

“…40). 73 Face-on orientation of the anchors allowed for the subsequent binding of crown-phthalocyanine molecules H 2 [(15C5) 4 Pc] via potassium ion bridges. This chemistry was utilized to form a heterogeneous bilayer, in which a single molecule thick adlayer brought an additional redox-state to the system, thus expanding the multistability of the system as a whole.…”

Unexpected Supramolecular Induced Redox Switching in Sandwich Gd Bisphthalocyaninate

“…Phthalocyanines (Pcs) and their lanthanide complexes are πconjugated electron-rich molecules, widely studied for various applications [1][2][3][4][5] . Phthalocyanines possess numerous aromatic πelectrons, which determine their photo-and redox-activity [6][7][8][9] , electrochromic 10,11 and semiconducting properties 12 . These properties are further enhanced in sandwich lanthanide complexes due to intramolecular π-π interactions and the intrinsic nature of the metal centres [13][14][15][16][17][18] .…”

Unexpected Supramolecular-Induced Redox Switching in Sandwich Gd Bisphthalocyaninate

“…Phthalocyanines (Pcs) and their lanthanide complexes are π-conjugated electron-rich molecules, widely studied for various applications. − Phthalocyanines possess numerous aromatic π-electrons, which determine their photo- and redox activity, − electrochromic, , and semiconducting properties . These properties are further enhanced in sandwich lanthanide complexes due to intramolecular π–π interactions and the intrinsic nature of the metal centers. − The electrochromic behavior of bisphthalocyaninates is determined by the ligand-centered redox conversion of M­(Pc) 2 between at least three forms of trivalent metal complexes: anionic [M 3+ (Pc 2– ) 2 ] – , neutral [(Pc –· )­M 3+ (Pc 2– )] 0 , and cationic [M 3+ (Pc – ) 2 ] + ones.…”