Coordination assembly and NIR photothermal conversion of Metal-organic framework based on 5-(2-cyanophenoxy) isophthalic acid

The development of new photothermal conversion materials in the field of metal-organic frameworks (MOFs) shows broad prospects, but their design synthesis and proper mechanism analysis are still full of huge challenge. Here, four novel MOFs were constructed with 5-(2-cyanophenoxy) isophthalic acid, {Ni(2-CB-IPA)(bpp)(H2O)}n (1), {Ni2(2-CB-IPA)2(bpa)2(H2O)2}n (2), {Co(2-CB-IPA)(bpp)}n (3), {Mn2(2-CB-IPA)2 (bpp)(H2O)2}n (4). (Where 2-CB-IPA = 5-(2-cyanophenoxy) isophthalic acid, bpa = 1,2-bis(4-pyridine)-ethane; and bpp = 1,3-bis(4-pyridyl)propane). The absorption peak at 730 nm in the near-infrared region indicates that different charge transfer interactions affect the photothermal conversion ability. Under laser irradiation (730 nm, 0.45 W cm−2), such compounds exhibit different and distinct warming processes (1 from 20.8 to 91.8 °C; 2 from 20.1 °C to 86.2 °C; 3 from 20.6 to 77.1 °C) except for compound 4. The excellent crystallinity of these materials after irradiation demonstrates excellent thermal stability and cycling durability. Subsequently, further research on the structure-activity relationship revealed that strong π - π interactions are also the reason for the excellent performance of NIR photothermal conversion of 1 under the premise of high NIR absorption. This work provides a visual platform for the photothermal phenomena of crystalline materials.