Theoretical Investigations On Recognition Mechanism For Identifying Small Molecules Of Several Luminescent Materials

In order to study the change of the luminescence mechanism of luminescent materialsafter interaction with the identified molecules,it is necessary to study the hydrogen bond of excited state in the system.In this paper,hydrogen bond is taken as the main research object,and we discussed the influence of photophysical processes of several luminescent materials after detecting small molecules.Combined with the corresponding experimental phenomena and related data,the hydrogen-bonded complexes of luminescent materials and identified molecules were constructed.According to the energy and distance of the two interacting molecules,we select the most reasonable geometry of the complexes to do further research.The density functional theory(DFT)and time-dependent density functional theory(TDDFT)are used to study the hydrogen bonding interactions between luminescent materials and the molecules which was detected.In order to reveal the influence of the identified molecules on the luminescent properties of the luminescent materials,a series of rate coefficients in the photophysical processes of luminescent materials and hydrogen bonded complexes are calculated,the effect of hydrogen bond on the luminescence process was analyzed.Revealing the recognition mechanism for identifying small molecules of luminesent materils.We used steady-state quenching to explain the recognition mechanism,study the photophysical processes of the hydrogen bonding complexes formed by the cyclometalated platinum complex and oxygen.We find the ground state of the special complex is in T0 states which is similar to the oxygen molecule.Among these complexes,the hydrogen bonded complexes with the lowest energy were chosen as the computational model for our study.By calculating and analyzing frontier molecular orbital and electron configuration we demonstrated that oxygen molecule can significantly alter the luminescent mechanism of cyclometalated platinum complex.Analyzing the rate coefficients for each transition process,indicating the photophysical process of cyclometalated platinum complex can be changed by oxygen molecule.And we studied the various competitive relationships among them to explain the corresponding experimental phenomenan.We studied the effect of nitrophenol on the fluorescence properties of porous material H-IC-MON and revealed the nature of fluorescence quenching phenomenon from the point of view of the hydrogen bond,the complexes formed by the nitrophenol and the porous materialH-IC-MON are investigated.We found that the hydrogen bond was used as the bridge for the charge transfer.The study of luminescent mechanism clearly revealed the effect of hydrogen bond on the luminescence process of the porous material H-IC-MON.Based on the detailed analysis of the geometry of the hydrogen bonded complexes in the ground state and the excited state,the frontier molecular orbital,the electronic configuration and the electron excitation energy,we inferred that the intermolecular hydrogen bond of this system was enhanced and the fluorescence was weakened or quenched.We investigated the hydrogen bonding interaction between salicylic acid and cross-conjugated molecule BBO cruciforms 2 and further verified that the Cross-conjugated molecule can be used as a sensor for detecting Salicylic acid.The Mulliken atomic charge,frontier molecular orbitals and electron configuration analysis indicated that the introduction of salicylic acid results in the change of luminescent mechanism of cross-conjugated molecular.According to change of hydrogen bond length,binding energy,nuclear magnetic resonance,infrared data in the ground state and excited state,combined with excitation energy analysis,it can be inferred that the intermolecular hydrogen bond was strengthened and fluorescence was decreasing or quenching after photo-excitation.