A Series of Lanthanide Metal–Organic Frameworks with Interesting Adjustable Photoluminescence Constructed by Helical Chains

Based on the isonicotinic acid (HIN=pyridine‐4‐carboxylic acid), seven lanthanide metal–organic frameworks (MOFs) with the formula [Ln(IN)₂L] (Ln=Eu ( 1 ), Tb ( 2 ), Er ( 3 ), Dy ( 4 ), Ho ( 5 ), Gd ( 6 ), La ( 7 ), L=OCH₂CH₂OH) have been synthesized by mixing Ln₂O₃ with HIN under solvothermal conditions, and characterized by single‐crystal X‐ray diffraction, powder X‐ray diffraction, infrared spectroscopy, and fluorescence spectroscopy. Crystal structural analysis shows that compounds 1–6 are isostructural, crystallize in a chiral space group P2₁2₁2₁, whereas compound 7 crystallizes in space group C2/c. Nevertheless, they all consist of new intertwined chains. Simultaneously, on the basis of the above‐mentioned compounds, we have realized a rational design strategy to form the doped Ln MOFs [(Eu_xTb_1?x)(IN)₂L] (x=0.35 ( 8 ), x=0.19 ( 9 ), x=0.06 ( 10 )) by utilizing Tb^III as the second “rare‐earth metal”. Interestingly, the photoluminescence of [(Eu_xTb_1?x)(IN)₂L] are not only adjustable by the ratios of Eu/Tb, but also temperature or excitation wavelength.