TY - JOUR

T1 - Systematic Investigation into the Photoswitching and Thermal Properties of Arylazopyrazole-based MOF Host–Guest Complexes

AU - Griffiths, Kieran

AU - Greenfield, Jake L.

AU - Halcovitch, Nathan R.

AU - Fuchter, Matthew J.

AU - Griffin, John M.

PY - 2023/10/4

Y1 - 2023/10/4

N2 - A series of arylazopyrazole-loaded metal–organic frameworks were synthesized with the general formula Zn2(BDC)2(DABCO)(AAP)x (BDC = 1,4-benzenedicarboxylate; DABCO = 1,4-diazabicyclo-[2.2.2]octane; AAP = arylazopyrazole guest). The empty framework adopts a large pore tetragonal structure. Upon occlusion of the E-AAP guests, the frameworks contract to form narrow pore tetragonal structures. The extent of framework contraction is dependent on guest shapes and pendant groups and ranges between 1.5 and 5.8%. When irradiated with 365 nm light, the framework expands due to the photoisomerization of E-AAP to Z-AAP. The proportion of Z-isomer at the photostationary state varies between 19 and 57% for the AAP guests studied and appears to be limited by the framework which inhibits further isomerization once fully expanded. Interestingly, confinement within the framework significantly extends the thermal half-life of the Z-AAP isomers to a maximum of approximately 56 years. This finding provides scope for the design of photoresponsive host–guest complexes with high stability of the metastable isomer for long-duration information or energy storage applications.

AB - A series of arylazopyrazole-loaded metal–organic frameworks were synthesized with the general formula Zn2(BDC)2(DABCO)(AAP)x (BDC = 1,4-benzenedicarboxylate; DABCO = 1,4-diazabicyclo-[2.2.2]octane; AAP = arylazopyrazole guest). The empty framework adopts a large pore tetragonal structure. Upon occlusion of the E-AAP guests, the frameworks contract to form narrow pore tetragonal structures. The extent of framework contraction is dependent on guest shapes and pendant groups and ranges between 1.5 and 5.8%. When irradiated with 365 nm light, the framework expands due to the photoisomerization of E-AAP to Z-AAP. The proportion of Z-isomer at the photostationary state varies between 19 and 57% for the AAP guests studied and appears to be limited by the framework which inhibits further isomerization once fully expanded. Interestingly, confinement within the framework significantly extends the thermal half-life of the Z-AAP isomers to a maximum of approximately 56 years. This finding provides scope for the design of photoresponsive host–guest complexes with high stability of the metastable isomer for long-duration information or energy storage applications.

KW - Condensed Matter Physics

KW - General Materials Science

KW - General Chemistry

U2 - 10.1021/acs.cgd.2c01384

DO - 10.1021/acs.cgd.2c01384

M3 - Journal article

VL - 23

SP - 7044

EP - 7052

JO - Crystal Growth and Design

JF - Crystal Growth and Design

SN - 1528-7483

IS - 10

ER -