Fluorescence spectra belongs to the emission spectrum. Compound absorbs energy to transit from the ground state to the excited state, then releases the energy in a non-radiative manner to relax to the minimum point of the excited state energy, and then de-excites to the ground state by releasing photons. This is a process of de-excitation from the minimum point of excited-state energy to the ground state, so the fluorescence wavelength can be predicted by finding the minimum point of excited-state energy. The prediction of fluorescence spectra through computational chemistry is a new field of study attempting to discover a more systematic and inexpensive method of producing fluorescent dyes. Reliable and accurate methods of predicting fluorescence spectra of highly complex molecules has been found by utilizing different levels of semi-empirical theory to simulate spectra.
Figure 1. (a) Fluorescence spectrum of DCFH. (b) and (c) Displays the fluorescence images of visible light-triggered ROS generation of HeLa cells. (d) ROS production mechanism of the GCNS upon visible light irradiation. (e) Western blot analysis of HSP70 levels in HeLa cells. (Liu, C.; et al. 2018)
Application of Fluorescence Spectroscopy
Fluorescence spectroscopy has been used in various fields, especially in non-destructive, microscopic, chemical analysis and imaging analysis. Fluorescence analysis can quickly provide qualitative or quantitative data.
- Nanotechnology: nanocrystals and nanotubes.
- Biology/Life science: the characterization of photoreceptors, the molecular mechanism of proton transport across membranes, and the complex microenvironment of molecules.
- Display technology: OLED.
- Carbon Nanotubes: nanomaterials.
- Water environment: solubility of organic matter.
- Food: gas sensors.
- Drugs: bioactivity of configuration, protein interaction, fluorescence immunoassay.
Our Fluorescence Spectrum Prediction Workflow
1. Customers provide the structure of the compound for which the fluorescence spectrum needs to be calculated.
2. 3D structure generation and optimization
- Gauss View
We use Gauss View to build a 3D structure, and small basis set is applied to optimize the ground state. A high-quality initial structure can be obtained by using a large basis set in time-dependent density functional theory (TD-DFT) calculations.
- OMEGA
Our experts generally use OMEGA for large-scale compound calculations. We apply OMEGA software to generate high-quality 3D structure utilizing 1D SMILES code and perform conformation search, and the global minimum point conformation is used for TD-DFT calculation.
- CONFLEX
We use CONFLEX to search for the conformation of the compound comprehensively, and calculate the conformational distribution. Conformation of the compound in aqueous solution can be obtained, and we use the conformation with the smallest Gibbs free energy for the TD-DFT calculation.
3. TD-DFT calculation
TD-DFT calculation is performed for structural optimization after obtaining the initial conformation.
4. Analysis of calculation results
We conduct the identification of the calculated wavelength of the last excited state according to the calculation results.
Alfa Chemistry's Advantages
- At Alfa Chemistry, various basis sets are available for structure optimization such as cam-B3LPY/6-31+g(d), cam-B3LPY/6-31+g(d) and so on.
- Our experts have rich experience in the calculation of excited states and electronic spectra.
Fluorescence spectrum prediction provides fluorescence spectra of highly complex molecules using TD-DFT calculation method. Our fluorescence spectrum prediction services remarkably reduce the cost, promote further experiments, and enhance the understanding of chemical process for customers worldwide. Our personalized and all-around services will satisfy your innovative study demands. If you are interested in our services, please don't hesitate to contact us. We are glad to cooperate with you and witness your success!
Reference
- Liu, C.; et al. Graphitic carbon nitride nanosheets as a multifunctional nanoplatform for photochemical internalization-enhanced photodynamic therapy. Journal of Materials Chemistry B. 2018, 6(47): 7908-7915.