Fig. 1. Structure design, types of stimuli, mechanisms of property modulation, and applications of stimuli-responsive photonic MOFs in this review.

Fig. 2. Schematic representation and strategies for functionalization of stimuli-responsive photonic MOFs. Stimuli-responsive MPUs (e.g., photochromic molecules and dyes) as a guest, as a ligands backbone, or as a ligands side group. Structural transformation process of flexible MOFs under external stimuli.

Fig. 3. Tuning of channel dimension in azo-IRMOF-74-III. Figures reproduced from Ref. 82.

Fig. 4. EnT on demand: BPMTC photoisomerization-directed behavior of Zn-MOF. Figures reproduced from Ref. 59.

Fig. 5. (a) Proposed mechanism of EnT in SO-PCN. (b) Illustration of reversible switching in SO-PCN. Figures reproduced from Ref. 83.

Fig. 6. (a) Schematic representation of structural moto-MOF1. (b) Photochemical and thermal isomerization of 1 incorporated in moto-MOF1. Figures reproduced from Ref. 15.

Fig. 7. (a) Schematic of the Cu2(F2AzoBDC)2(dabco) containing the fluorinated AZOs side groups. (b) CD spectra of the Cu2(F2AzoBDC)2(dabco) upon right- and left-CPL of 400 nm wavelength irradiation. Figures reproduced from Ref. 86.

Fig. 8. Structural representation of photo-induced lattice contraction. (a) and (b) View along the b axis of 1 and 1A. (c) View of the head-to-tail molecular packing of photoreactive ligands in 1. (d) Structure of photodimerization ligand in 1A. Sky-blue arrows represent significant separations in 1 and 1A. Figures reproduced from Ref. 13.

Fig. 9. (a) Schematic illustration of the zwitterionic and neutral tetracarboxylate linkers for the preparation of two-photon responsive MOFs and the femtosecond laser writing MOF single crystal. (b) Top view of TPEF image of a 2D code stack. Scale bar, 25μm. Reconstructed lateral image along the indicated line in the left picture. Figures reproduced from Ref. 94.

Fig. 10. (a) Proposed photodimerization reaction and restored process of ANT molecules upon UV light irradiation and thermal dissociation in the ZIF-8 cage. (b) Photopatterning on ANT@ZIF-8 based paper. Images of photopatterned QR codes under UV light (left). Decoding of QR codes with a smartphone (right). Figures reproduced from Ref. 112.

Fig. 11. (a) Schematic illustration of the photo-stimuli-responsive luminescence of the ZJU-128⊃SP. (b) Emission spectra of ZJU-128⊃SP excited at 395 nm under the UV (365 nm) irradiation with different times. (c) Reversible emission intensity changes at 650 nm upon alternating UV and visible light irradiation. (d) Photographs of ZJU-128⊃SP film under a 365 nm UV lamp irradiation with different times. Figures reproduced from Ref. 116.

Fig. 12. (a) Schematic illustration of the sensing of CO2 via monitoring of the configuration-related fluorescence emission of DSB in a flexible PCP framework. Figures reproduced from Ref. 118. (b) Schematic illustration of the breathing behavior of the NH2-MIL-53(Al) as an NLO switch. Figures reproduced from Ref. 119.

Fig. 13. (a) Schematic illustrating the reversible motion of the microscissor lift in PCN-128W and PCN-128Y. (b) Fluorescent spectra of PCN-128W and PCN-128Y at room temperature. Figures reproduced from Ref. 121.

Fig. 14. (a) Structural characters and (b) selected photographic images in correlation with pressure-induced 1/2/3PEF of the AIE MOFs. Figures reproduced from Ref. 123.

Fig. 15. (a) Structure of Tb(BTC)(H2O)6. (b) Optical images of Tb(BTC)(H2O)6 at 1 atm and upon complete release of the pressure. Figures reproduced from Ref. 126.

Fig. 16. (a), (b) Structure and (c) red color of ZJU-68⊃DMASM crystal viewed along the crystallographic c direction. Intensity-dependent emission spectra of 3PP (d) WGMs and (e) F-P from crystal with pump/emission-detected polarization combinations at two angles θ=0deg and θ=90deg, excited at 1380 nm. Figures reproduced from Ref. 135.

Fig. 17. Aligned dyes in a ZJU-24-Eu⊃DSM crystal for switchable polarized-excitation-responsive SHG and TPP lasing. Figures reproduced from Ref. 137.

Fig. 18. Schematic diagram of sandwich-like MOF-based mixed-matrix membranes to realize NLO switching. Figures reproduced from Ref. 141.

Fig. 19. Chiral and SHG-active MOFs formed in solution and on surfaces. Figures reproduced from Ref. 143.

Fig. 20. (a) Layered structure of a MOF microplate with stable π–π interaction between adjacent layers. (b) Three photon-pumped lasing spectra recorded at four different emission polarization angles (from 0 deg to 90 deg). Figures reproduced from Ref. 148.

Fig. 21. Series of highly efficient MPA of zinc-AIEgen MOFs. Figures reproduced from Ref. 150.

Fig. 22. Illustration of the structure of TDC-MOF-8. Figures reproduced from Ref. 151.

Table 1. Features and suggested or examined applications of select stimuli-responsive photonic MOFs.