Loading...

Insight into the Coordination Varieties of a NxO2 Peraza-Crown Macrocyclic Ligand Group Anchored by Pyridine Side Arms

Asadi Mofarrah, Leila | 2023

31 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 56784 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Ghanbari, Bahram
  7. Abstract:
  8. In this treatise, the effect of type of macrocycle ring on the final structure of the complexes which made from them was investigated. For this purpose, by changing the 15-membered benzylic macrocycle with two pyridine pendant arms (2p), which was studied in our previous experiments (the effect of the position of the nitrogen atom of the pyridine ring in the side arm and the type of metal ion in the geometry of its complexes), two new macrocycles by adding a naphthalene rings instead of benzylic ringsin in 2p and increasing the ring size from 15 to 17 members, Lpy-naph and Lpy-benz were symthesized respectively. The molecular formula and structure of Lpy-naph and Lpy-benz were confirmed by CHN elemental analysis and FT-IR spectroscopy, 1H NMR and 13C NMR. The coordination chemistry of macrocycles Lpy-naph and Lpy-benz with CoCl2.6H2O, CdCl2.4H2O and CoCl2.6H2O, CoBr2.6H2O salts were investigated respectively. The slow diffusion of the macrocycles solution in DMF to the metal salts solution, afforded suitable crystals for X-ray diffraction studiese. The molecular formula and structure of these crystals were confirmed by elemental analysis of CHN and SXRD, FT-IR spectroscopy. SXRD analyzes showed that Lpy-naph with cobalt(II) and cadmium(II), made two cyclic dimers with the general formula M2L2 (complexes 1 and 2) and Lpy-benz with CoCl2.6H2O, CoBr2.6H2O, formed two metal organic cages that had lantern shaped structures with a general formula M2L4, in which two chlorine and bromine ions were present as guests in their cavity (complexes 3 and 4). These structures were new geometries that were not observed in the 2p complexes, so the role of the macrocycle ring type in guiding of final complex structures was clarified. Also, the emission properties of complexes 2, 3 and 4 were investigated. Fluorescence studies showed that the emission of complex 2 in the presence of ortho-, meta- and para-xylene decreases with different amounts and competition experiments confirmed that this complex is a luminogenic sensor for ortho-xylene, while the color of the suspensions of this complex in the presence of three Xylene isomers are different, so 2 is considered as a chromogenic sensor for all three xylene isomers too. Theoretical studies determined the origin of the Fluorescence emission of 2 and confirmed experimental data based on the interaction of 2 with xylene isomers in this manner: ortho-xylene ˃ meta-xylene ˃ para-xylene. . FT-IR, 1H NMR and thermogravimetric analysis (TGA) experiments proved that complex 2 is capable of adsorbing ortho- and meta-xylene, while para-xylene is not adsorbed. Furthermore, 2 could catalyze the oxidation process of ortho- and meta-xylene, while it is ineffective for para-xylene, which was confirmed by GC-mass data. Fluorescence tests also showed that 3 is able to detect nitroaromatic compounds with emission quenching, which has greater selectivity and sensitivity toward para-nitroaniline (PNA) with a detection limit of 4.24 ppm. Adding 50μL of PNA and ortho-nitrophenol (ONP) to the ethanolic suspension of 3 leads to the Fluorescence emission red shift by 87 and 24 nm respectively, which are much higher than the values that observed in the presence of other nitroaromatic compounds. Furthermore, 3 can discriminate the ONP isomer from para-nitrophenol (PNP) and the three ortho-, meta-, para-dinitrobenzene isomers from eachother. Replacement of chloride with bromide ligands in cage 3 leads to form cage 4, which is more electron donner than 3. Fluorescence experiments showed that 4 is more sensitive to nitroaromatics but less selective than 3. Meanwhile, 3 was able to catalyze the Mizorocki-Hack reaction.
  9. Keywords:
  10. Azacrown Macrocycle with Pyridine Arms ; Supramolecular Chemistry ; Macrocycle ; Azacrown ; Pyridine Ligands ; Metal-Organic Cages ; Coordination Mechanism ; Host-Guest Complex ; Anionic Guest

 Digital Object List

 Bookmark

No TOC