Photochemical- and pH-switching Properties of a New Photoelastic Ligand Based Upon Azobenzene. Basicity and Anion Binding

Andrea Bencini; Antonio Bianchi; Claudia Giorgi; Emiliano Romagnoli; Carlos Lodeiro; André Saint-Maurice; Fernando Pina; Barbara Valtancoli

doi:10.1080/10610270108027482

Photochemical- and pH-switching Properties of a New Photoelastic Ligand Based Upon Azobenzene. Basicity and Anion Binding

Andrea Bencini, Antonio Bianchi, Claudia Giorgi, Emiliano Romagnoli, Carlos Lodeiro, André Saint-Maurice, Fernando Pina, Barbara Valtancoli

Research output: Contribution to journal › Article › peer-review

18 Citations (Scopus)

Abstract

The synthesis of a new cylindrical macrotricyclic ligand (L) based upon two 1,4,7,13-tetramethyl-1,4,7, 10,13,16-hexaazacyclooctadecane rings connected via two azobenzene pillars is described. The ligands displays photoelastic properties: light absorption at 366nm produces trans→cis isomerization of the azobenzene moieties with formation of trans-cis (L_E-Z) and cis-cis (L_Z-Z) isomers. Recovery of the thermodynamically more stable trans-trans (L_E-E) isomer can be obtained by thermal back-isomerization or visible light (430nm) absorption. The isomeric composition of L solution depends upon pH: for pH < 5.5 the L_E-E form is the unique species in solution, while increasing amounts of Z species are formed at increasing pH. The protonation constants of L_E-E have been determined in 0.1 mol dm^-3 Me₄NNO₃ solution at 298.1 ± 0.1 K. The protonated species of L form stable inclusion complexes with anionic species such as [Co(CN)₆]^3-.

Original language	English
Pages (from-to)	277-285
Number of pages	9
Journal	Supramolecular Chemistry
Volume	13
Issue number	2
DOIs	https://doi.org/10.1080/10610270108027482
Publication status	Published - 1 Jan 2001

Keywords

Anion coordination
Chemical switches
Macrocycles
Photoelastic ligands

Access to Document

10.1080/10610270108027482

Cite this

@article{7107d5db7c8c41b1b7fa6e8633a055b0,

title = "Photochemical- and pH-switching Properties of a New Photoelastic Ligand Based Upon Azobenzene. Basicity and Anion Binding",

abstract = "The synthesis of a new cylindrical macrotricyclic ligand (L) based upon two 1,4,7,13-tetramethyl-1,4,7, 10,13,16-hexaazacyclooctadecane rings connected via two azobenzene pillars is described. The ligands displays photoelastic properties: light absorption at 366nm produces trans→cis isomerization of the azobenzene moieties with formation of trans-cis (LE-Z) and cis-cis (LZ-Z) isomers. Recovery of the thermodynamically more stable trans-trans (LE-E) isomer can be obtained by thermal back-isomerization or visible light (430nm) absorption. The isomeric composition of L solution depends upon pH: for pH < 5.5 the LE-E form is the unique species in solution, while increasing amounts of Z species are formed at increasing pH. The protonation constants of LE-E have been determined in 0.1 mol dm-3 Me4NNO3 solution at 298.1 ± 0.1 K. The protonated species of L form stable inclusion complexes with anionic species such as [Co(CN)6]3-.",

keywords = "Anion coordination, Chemical switches, Macrocycles, Photoelastic ligands",

author = "Andrea Bencini and Antonio Bianchi and Claudia Giorgi and Emiliano Romagnoli and Carlos Lodeiro and Andr{\'e} Saint-Maurice and Fernando Pina and Barbara Valtancoli",

note = "This work has been supported by the Minister0 dell'universita e della Ricerca Scientifica e Tecnologica (MURST, Rome) within the program COFIN 98, in Italy, and Fundagiio para a Cigncia e Tecnologia (FCT) in Portugal. A.S.-M. thanks a grant PRAXIS XXI from FCT.",

year = "2001",

month = jan,

day = "1",

doi = "10.1080/10610270108027482",

language = "English",

volume = "13",

pages = "277--285",

journal = "Supramolecular Chemistry",

issn = "1061-0278",

publisher = "Taylor \& Francis",

number = "2",

}

TY - JOUR

T1 - Photochemical- and pH-switching Properties of a New Photoelastic Ligand Based Upon Azobenzene. Basicity and Anion Binding

AU - Bencini, Andrea

AU - Bianchi, Antonio

AU - Giorgi, Claudia

AU - Romagnoli, Emiliano

AU - Lodeiro, Carlos

AU - Saint-Maurice, André

AU - Pina, Fernando

AU - Valtancoli, Barbara

N1 - This work has been supported by the Minister0 dell'universita e della Ricerca Scientifica e Tecnologica (MURST, Rome) within the program COFIN 98, in Italy, and Fundagiio para a Cigncia e Tecnologia (FCT) in Portugal. A.S.-M. thanks a grant PRAXIS XXI from FCT.

PY - 2001/1/1

Y1 - 2001/1/1

N2 - The synthesis of a new cylindrical macrotricyclic ligand (L) based upon two 1,4,7,13-tetramethyl-1,4,7, 10,13,16-hexaazacyclooctadecane rings connected via two azobenzene pillars is described. The ligands displays photoelastic properties: light absorption at 366nm produces trans→cis isomerization of the azobenzene moieties with formation of trans-cis (LE-Z) and cis-cis (LZ-Z) isomers. Recovery of the thermodynamically more stable trans-trans (LE-E) isomer can be obtained by thermal back-isomerization or visible light (430nm) absorption. The isomeric composition of L solution depends upon pH: for pH < 5.5 the LE-E form is the unique species in solution, while increasing amounts of Z species are formed at increasing pH. The protonation constants of LE-E have been determined in 0.1 mol dm-3 Me4NNO3 solution at 298.1 ± 0.1 K. The protonated species of L form stable inclusion complexes with anionic species such as [Co(CN)6]3-.

AB - The synthesis of a new cylindrical macrotricyclic ligand (L) based upon two 1,4,7,13-tetramethyl-1,4,7, 10,13,16-hexaazacyclooctadecane rings connected via two azobenzene pillars is described. The ligands displays photoelastic properties: light absorption at 366nm produces trans→cis isomerization of the azobenzene moieties with formation of trans-cis (LE-Z) and cis-cis (LZ-Z) isomers. Recovery of the thermodynamically more stable trans-trans (LE-E) isomer can be obtained by thermal back-isomerization or visible light (430nm) absorption. The isomeric composition of L solution depends upon pH: for pH < 5.5 the LE-E form is the unique species in solution, while increasing amounts of Z species are formed at increasing pH. The protonation constants of LE-E have been determined in 0.1 mol dm-3 Me4NNO3 solution at 298.1 ± 0.1 K. The protonated species of L form stable inclusion complexes with anionic species such as [Co(CN)6]3-.

KW - Anion coordination

KW - Chemical switches

KW - Macrocycles

KW - Photoelastic ligands

UR - https://www.scopus.com/pages/publications/0035564693

U2 - 10.1080/10610270108027482

DO - 10.1080/10610270108027482

M3 - Article

AN - SCOPUS:0035564693

SN - 1061-0278

VL - 13

SP - 277

EP - 285

JO - Supramolecular Chemistry

JF - Supramolecular Chemistry

IS - 2

ER -

Photochemical- and pH-switching Properties of a New Photoelastic Ligand Based Upon Azobenzene. Basicity and Anion Binding

Abstract

Keywords

Access to Document

Other files and links

Fingerprint

Cite this