Multicomponent Anti-Kasha?s Rule Emission from Nanotubular Metal-Organic Frameworks for Selective Detection of Small Molecules

The peak photoluminescence (PL) of conventional fluorophores is independent of the excitation wavelength (called Kasha's rule), while the search of metal-organic framework materials with the so-called anti-Kasha's rule emission remains very limited. Herein, we report the observation of anti-Kasha's rule emission in a multicomponent PL three-dimensional nanotubular metal-organic framework (abbr. MOF-NT), [Zn(mu-L)(mu-bix)]n center dot 0.33nH2O [H2L = biphenyl-3,5-dicarboxylic acid; bix = 1,4-bis(imidazole-1-ylmethyl)benzene]. The MOF-NT crystalline sample represents a notable example of strong excitation-dependent fluorescence from the ultraviolet to the visible spectral region. Moreover, by virtue of electronic flexibility and high PL efficiency, MOF-NT shows a discriminative PL response between isomeric nitroaromatic compounds. The work demonstrated the intrinsic anti-Kasha's rule emission in the crystalline-state MOF materials, providing new visions for the development of advanced solid-state emissive materials.

Automated summary

In this study, the observation of anti-Kasha's rule emission in a multicomponent three-dimensional nanotubular metal-organic framework (MOF-NT) was reported. The MOF-NT displayed strong excitation-dependent fluorescence from the ultraviolet to the visible spectral region and showed a discriminative photoluminescence response to isomeric nitroaromatic compounds. This work demonstrated the intrinsic anti-Kasha's rule emission in crystalline-state MOF materials and provided new perspectives for the development of advanced solid-state emissive materials.