Synthesis, Structure, and Photophysical Properties of New Gallium(III) and Indium(III) 15-Crown-5-Substituted Porphyrina
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SCALE AND NANOSTRUCTURED MATERIALS AND COATINGS
Synthesis, Structure, and Photophysical Properties of New Gallium(III) and Indium(III) 15-Crown-5-Substituted Porphyrinates A. Yu. Chernyad’eva, * and A. Yu. Tsivadzea aFrumkin
Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia *e-mail: [email protected] Received February 19, 2020; revised April 2, 2020; accepted April 9, 2020
Abstract—New indium(III) and gallium(III) meso-tetra(benzo-15-crown-5) porphyrinates are synthesized. The structure of complexes is determined from spectroscopy data. A comparative analysis of the luminescent properties of new compounds at temperatures of 298 and 77 K is performed. The indium(III) and gallium(III) crown-porphyrinates are established to exhibit fluorescent behavior at a temperature of 298 K, while phosphorescence radiation is totally absent at this temperature for both complexes. At the nitrogen boiling point (77 K), the two complexes give off both fluorescent and phosphorescent radiation. The prepared compounds can be interesting as luminescent temperature sensors operating on the basis on the intensity ratio between fluorescence and phosphorescence transitions in the temperature range of 77–203 K. The energies of triplet levels in indium(III) and gallium(III) crown-porphyrinate molecules suggest that the new compounds are capable of producing singlet molecular oxygen. Evidently, the new compounds can also be of interest as photosensitizers in photodynamic therapy of tumors. DOI: 10.1134/S207020512005007X
INTRODUCTION Crown ether-substituted porphyrins attract interest as compounds that can form supramolecular associates with alkali and earth alkaline metals, ammonium cations [1, 2], and neutral molecules like fullerenes [3]. Supramolecular associates of crown-porphyrins may be of interest as promising compounds for metal cation transport through the cell membrane [4], and associates between metal crown-porphyrinates and fullerenes are interesting for use as active components of composite photovoltaic transducers [3, 5]. In our earlier studies, we found that in a polymer matrix (polystyrene) rhodium(III) and palladium(IV) crownporphyrinates with a moderate “heavy atom effect” behave as luminescent temperature sensors by changing the intensity ratio between phosphorescent and fluorescent emissions of their molecules [6, 7]. Such composite materials (a metal porphyrinate incorporated into polystyrene) can be applied onto the surface of objects of interest, provided that there is chemical affinity between the polymer base and the surface of interest. Metal porphyrinate molecules can be applied, without a polymer base, onto the surface of porous materials (e.g., clay) or materials with a complex surface topography and hollow cavities, (e.g., silica gel) in which metal crown-porphyrinate molecules—disks with a diameter of ~2.5 nm—can be deposited. However, in the absence of a polymer base, we have to deal with the issue of interaction between dye molecules and atmospheric oxygen by p
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