The role of the metal ion in the photophysical behavior of Co(II), Ni(II), and Cu(II) octabutoxynaphthalocyanines: insights from ultra-fast time-resolved spectroscopy and DFT/TDDFT calculations

2010 ◽  
Vol 14 (08) ◽  
pp. 689-700 ◽  
Author(s):  
Giampaolo Ricciardi ◽  
Alexandra V. Soldatova ◽  
Angela Rosa
Keyword(s):  
Density Functional Theory ◽  
Metal Ion ◽  
Density Functional ◽  
Transient Absorption ◽  
Density Functional Theory Calculations ◽  
Fast Time ◽  
Central Metal ◽  
Functional Theory ◽  
Time Resolved ◽  
Deactivation Mechanism

The photo-deactivation mechanism of the MNc(OBu)8 (M = Co, Ni, Cu) series of complexes is reviewed, with special emphasis on the role played by the central metal. Ultra-fast transient absorption experiments and Density Functional Theory and time-dependent Density Functional Theory calculations consistently show that the central metal modifies the photo-deactivation mechanism of the investigated complexes by inducing substantial changes in the nature and energy of the excited states lying between the photo-generated state and the ground state.

scholarly journals Ground- and excited-state characteristics in photovoltaic polymer N2200

RSC Advances ◽  
2021 ◽  
Author(s):  
Guanzhao Wen ◽  
Xianshao Zou ◽  
Rong Hu ◽  
Jun Peng ◽  
Zhifeng Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Steady State ◽  
Excited States ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Time Dependent ◽  
Functional Theory ◽  
Time Resolved ◽  
Dependent Density

Ground- and excited-states properties of N2200 have been studied by steady-state and time-resolved spectroscopies as well as time-dependent density functional theory calculations.

scholarly journals Towards hydrophobic carminic acid derivatives and their incorporation in polyacrylates

2018 ◽  
Vol 5 (7) ◽  
pp. 172399 ◽  
Author(s):  
Luca Gabrielli ◽  
Davide Origgi ◽  
Giuseppe Zampella ◽  
Luca Bertini ◽  
Simone Bonetti ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dimethyl Sulfoxide ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Spectroscopic Properties ◽  
Carminic Acid ◽  
Functional Theory ◽  
Time Resolved ◽  
Sugar Ring ◽  
Time Resolved Photoluminescence

Carminic acid, a natural hydrophilic dye extensively used in the food and cosmetic industries, is converted in hydrophobic dyes by acetylation or pivaloylation. These derivatives are successfully used as biocolourants for rubber objects. In this paper, spectroscopic properties of the carminic acid derivatives in dimethyl sulfoxide and in polybutylacrylate are studied by means of photoluminescence and time-resolved photoluminescence decays, revealing a hypsochromic effect due to the presence of bulky substituents as the acetyl or pivaloyl groups. Molecular mechanics and density functional theory calculations confirm the disruption of planarity between the sugar ring and the anthraquinoid system determined by the esterification.

Electronic structures, spectroscopic properties, and reaction activities of porphyrins with alkali metal ions: density functional theory approach to the central metal effects

2012 ◽  
Vol 16 (07n08) ◽  
pp. 927-934 ◽  
Author(s):  
Luyang Zhao ◽  
Dongdong Qi ◽  
Lijuan Zhang ◽  
Ming Bai ◽  
Xue Cai
Keyword(s):  
Density Functional Theory ◽  
Alkali Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Density Functional ◽  
State Transitions ◽  
Theory Approach ◽  
Central Metal ◽  
Functional Theory ◽  
Molecular Stability

Density functional theory (DFT) calculation method was employed to investigate a series of nine alkali metal porphyrins (alk-Pors), namely HLiPor , HNaPor , HKPor , Li2Por , LiNaPor , LiKPor , Na2Por , NaKPor , and K2Por . These molecules show different configurations depending on different metal ions which locate over the central hole of the porphyrin ligand. Alk-Pors with larger-radius metal ion have smaller binding energy and thus is more difficult to keep stable. Further detailed molecular stability analysis was carried out by noncovalent interaction and electrostatic interaction via RDG and NBO charge distribution. UV-vis spectra of these nine compounds also show different spectral shapes depending on the central metals, and the dominant state transitions with high degeneracy are revealed to be influenced by high molecular symmetric order. Finally their difference in reactivity due to the electronegativity of central metals and the nature of porphyrin rings are predicted by electrostatic potential and Fukui functions.

scholarly journals Photochemical α-Cleavage Reaction of 3’,5’-Dimethoxybenzoin: A Combined Time-Resolved Spectroscopy and Computational Chemistry Study

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3548
Author(s):  
Yuanchun Li ◽  
Xiting Zhang ◽  
Zhiping Yan ◽  
Lili Du ◽  
Wenjian Tang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Quantum Yield ◽  
Dft Calculations ◽  
Density Functional ◽  
Transient Absorption ◽  
Type I ◽  
Functional Theory ◽  
Time Resolved ◽  
Norrish Type ◽  
Intramolecular Hydrogen

Benzoin is one of the most commonly used photoinitiators to induce free radical polymerization. Here, improved benzoin properties could be accomplished by the introduction of two methoxy substituents, leading to the formation of 3’,5’-dimethoxybenzoin (DMB) which has a higher photo-cleavage quantum yield (0.54) than benzoin (0.35). To elucidate the underlying reaction mechanisms of DMB and obtain direct information of the transient species involved, femtosecond transient absorption (fs-TA) and nanosecond transient absorption (ns-TA) spectroscopic experiments in conjunction with density functional theory/time-dependent density functional theory (DFT/TD-DFT) calculations were performed. It was found that the photo-induced α-cleavage (Norrish Type I reaction) of DMB occurred from the nπ* triplet state after a rapid intersystem crossing (ISC) process (7.6 ps), leading to the generation of phenyl radicals on the picosecond time scale. Compared with Benzoin, DMB possesses two methoxy groups which are able to stabilize the alcohol radical and thus result in a stronger driving force for cleavage and a higher quantum yield of photodissociation. Two stable conformations (cis-DMB and trans-DMB) at ground state were found via DFT calculations. The influence of the intramolecular hydrogen bond on the α-cleavage of DMB was elaborated.

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