Near-infrared-emissive metal–organic frameworks

Abstract

We describe the recent progress in near-infrared-emissive metal–organic frameworks, and especially highlight their appealing applications in bio-imaging, sensing and barcoding.

Metal–organic framework thin films as versatile chemical sensing materials

“…Terbium and/or europium are most often used due to their intrinsically high quantum yield in the visible emission range (relative to the other lanthanides), 153,154 while nearinfrared (NIR)-emitting MOFs usually incorporate ytterbium, neodymium, and/or erbium. 155 NIR-emitting MOFs are less commonly used in part due to higher equipment costs for NIR detection; however, emission in this range is optimal for optical fiber and biological applications. 155 Importantly, while lanthanides produce intense, narrow emission bands that are desirable for sensing applications, the absorption transitions that give rise to this emission are parity forbidden; therefore, sensitizer molecules (such as the linkers used in MOFs) are typically required to first transfer energy to the lanthanide metal centers.…”

“…155 NIR-emitting MOFs are less commonly used in part due to higher equipment costs for NIR detection; however, emission in this range is optimal for optical fiber and biological applications. 155 Importantly, while lanthanides produce intense, narrow emission bands that are desirable for sensing applications, the absorption transitions that give rise to this emission are parity forbidden; therefore, sensitizer molecules (such as the linkers used in MOFs) are typically required to first transfer energy to the lanthanide metal centers. 90 In rare cases, MOFs may also be designed with emissive uranyl [UO 2 ] 2+ centers.…”

Development of biological metal–organic frameworks designed for biomedical applications: from bio-sensing/bio-imaging to disease treatment

“…For bio-sensing or bio-imaging, the luminescence properties of MOFs can be bestowed by the introduction of either organic ligands or metal centers (ions or clusters) with intrinsic luminescence properties, or luminescent guest molecules or ions. [15][16][17] For drug delivery or disease treatment, several limitations of guest drugs can be well resolved aer they are encapsulated in the pore structures or constructed in the frameworks of MOFs, including poor solubility, blood instability, and systemic toxicity due to the wide drug distribution in the whole body.…”

PPV-type π-conjugated polymers based on hypervalent tin(IV)-fused azobenzene complexes showing near-infrared absorption and emission

“…Because of unique physical properties of near-infrared (NIR) light, such as invisibility and high permeability in various media, NIR-absorptive and emissive substances are versatile in a wide variety of applications, such as developments of security inks, night vision cameras, bioimaging probes, sensors, and optical communication media [1][2][3][4][5][6][7][8]. To realize future technologies relating with NIR light, not only photochemical functions but also material properties, such as processability and solubility in conventional media, are essential.…”