Photochromism and Dual-Color Fluorescence in a Polyoxometalate-Benzospiropyran Molecular Switch.
The photophysical properties of a Keggin-type polyoxometalate (POM) covalently bounded to a benzospiropyran (BSPR) unit have been investigated. These studies reveal that both closed and open forms are emissive with distinct spectral features (λem(closed form)=530 nm, λem(open form)=670 nm) and that the fluorescence of the BSPR unit of the hybrid is considerably enhanced compared to BSPR parent compounds. While the fluorescence excitation energy of the BSPR reference compounds (370 nm) is close to the intense absorption responsible of the photochromic character (350 nm), the fluorescence excitation of the hybrid is shifted to lower energy (400 nm), improving the population of the emissive state. Combined NOESY NMR and theoretical calculations of the closed form of the hybrid give an intimate understanding of the conformation adopted by the hybrid and show that the nitroaryl moieties of the BSPR is folded toward the POM, which should affect the electronic properties of the BSPR.
Institut Parisien de Chimie Moléculaire UMR CNRS 8232, Sorbonne Universités, UPMC-Paris06, 4 Place Jussieu, F-, 75005, Paris, France.
Arnaud
A
Parrot
Institut Parisien de Chimie Moléculaire UMR CNRS 8232, Sorbonne Universités, UPMC-Paris06, 4 Place Jussieu, F-, 75005, Paris, France.
Aurélie
A
Bernard
Institut Parisien de Chimie Moléculaire UMR CNRS 8232, Sorbonne Universités, UPMC-Paris06, 4 Place Jussieu, F-, 75005, Paris, France.
Aurélie
A
Jacquart
Catalan Institute of Chemical Research (ICIQ), The Barcelona Institute of Science and Technology, Avinguda dels Països Catalans 16, 43007, Tarragona, Spain.
Stefano Artin
0000-0003-0122-8499
SA
Serapian
Catalan Institute of Chemical Research (ICIQ), The Barcelona Institute of Science and Technology, Avinguda dels Països Catalans 16, 43007, Tarragona, Spain.|Department de Química Física i Inorgànica, Universitat Rovira i Virgili, Avda. Marcel.li Domingo s/n., Tarragona, Spain.
Carles
C
Bo
Institut Parisien de Chimie Moléculaire UMR CNRS 8232, Sorbonne Universités, UPMC-Paris06, 4 Place Jussieu, F-, 75005, Paris, France.
Etienne
0000-0002-8637-2707
E
Derat
Institut Lavoisier de Versailles, UMR CNRS 8180, Université de Versailles Saint-Quentin en Yvelines, Université Paris Saclay, 45 Avenue des Etats-Unis, F-, 78035, Versailles cedex, France.
Olivier
O
Oms
Institut Lavoisier de Versailles, UMR CNRS 8180, Université de Versailles Saint-Quentin en Yvelines, Université Paris Saclay, 45 Avenue des Etats-Unis, F-, 78035, Versailles cedex, France.
Anne
0000-0001-7940-4152
A
Dolbecq
Institut Parisien de Chimie Moléculaire UMR CNRS 8232, Sorbonne Universités, UPMC-Paris06, 4 Place Jussieu, F-, 75005, Paris, France.
Anna
A
Proust
PPSM, UMR CNRS 8531, ENS Cachan, 61 av. Président Wilson, 94235, Cachan cedex, France.
Rémi
0000-0001-5612-8327
R
Métivier
Institut Lavoisier de Versailles, UMR CNRS 8180, Université de Versailles Saint-Quentin en Yvelines, Université Paris Saclay, 45 Avenue des Etats-Unis, F-, 78035, Versailles cedex, France.
Pierre
0000-0002-8519-7943
P
Mialane
Institut Parisien de Chimie Moléculaire UMR CNRS 8232, Sorbonne Universités, UPMC-Paris06, 4 Place Jussieu, F-, 75005, Paris, France.
Guillaume
0000-0002-9849-4939
G
Izzet
density functional calculations; fluorescence; molecular photoswitches; photochromism; polyoxometalates