Molecular photophysics and laser control: Small molecules to fluorescent proteins

该研究的重点是开发和利用理论和计算方法，以了解和预测生物成像和新材料的分子结构和特性，以及控制分子量子动力学。实验测量需要补充的理论和计算研究来解释，更重要的是，将观察到的行为推广到其他系统。虽然重点是详细了解激发电子态，相应的光谱特性（单光子吸收，双光子吸收，荧光，磷光，.），和潜在的动力学，要研究的问题是多种多样的：（1）荧光蛋白是有用的探针的生物机制，功能和结构的分子和细胞生物学。设计具有优良双光子吸收的FP已经引起了人们极大的兴趣。我们将根据非典型氨基酸（ncAAs）的双光子吸收特性，通过计算筛选FP。由于将ncAAs掺入蛋白质是一项具有挑战性的任务，因此对有前途的系统进行计算指导至关重要。(2)我们将探索最近合成的荧光核碱基类似物（天然核碱基是非荧光的），以合理化结构和物理性质之间的联系。为了评估它们在生物成像中的用途，我们将研究它们与天然核碱基的结合以及随后对吸收/荧光特性的影响。(3)将开发用于模拟共振拉曼光谱的计算工具。(4)BODIPY家族分子由于其优异的物理化学性质而被广泛使用，即，可调吸收波长、大消光系数和高量子产率。将检查取代的BODIPY和BODIPY二聚体的各种用途，例如，成像，分子光子学(5)我们将计算基于含铋化合物的新磷光材料的物理性质;具有改进的光谱特性的新材料的合理设计可以节省无数的实验。(6)使用定制的激光场来控制量子动力学在理论和实验上都是成熟的。从中红外到紫外的成形激光源的持续发展已经导致了对多种物理和光化学现象的控制，例如，振转和/或电子态布居转移、光致异构化。这些实验的一个重要补充是对导致控制的机制的详细理解。拟议的研究将进一步发展和应用方法，检查激光控制多原子分子。应用将包括光异构化，特别是光开关蛋白质。

The research is focused on the development and utilization of theoretical and computational methods for understanding and predicting the structure and properties of molecules underlying biological imaging and new materials as well as for controlling molecular quantum dynamics. Experimental measurements require complementary theoretical and computational study to interpret, and, more importantly, to generalize the observed behaviour to other systems. While the emphasis is on a detailed understanding of excited electronic states, corresponding spectroscopic properties (1-photon absorption, two-photon absorption, fluorescence, phosphorescence,.), and underlying dynamics, the problems to be studied are diverse: (1) Fluorescent proteins are useful probes of biological mechanisms, functions, and structures in molecular and cell biology. There has been great interest in designing FPs with excellent two-photon absorption. We will screen computationally FPs based on non-canonical amino acids (ncAAs) for their two-photon absorption properties. Since the incorporation of ncAAs into proteins is a challenging task experimentally, computational guidance on promising systems is critically important. (2) We will explore recently synthesized fluorescent nucleobase analogs (the natural nucleobases are non-fluorescent) to rationalize the connections between structure and photophysical properties. To assess their use in biological imaging, we will study their binding to natural nucleobases and subsequent effects on absorption/fluorescence properties. (3) Computational tools will be developed for simulating resonance Raman spectra. (4) The BODIPY family of molecules is used widely due to their excellent photophysical properties, i.e., tunable absorption wavelengths, large extinction coefficients, and high quantum yields. Substituted-BODIPY and BODIPY dimers will be examined for a variety of uses, e.g., imaging, molecular photonics. (5) We will compute the photophysical properties of new phosphorescent materials based on bismuth-containing compounds; the rational design of new materials with improved spectral characteristics can save countless experiments. (6) Using tailored laser fields to control quantum dynamics is well-established theoretically and experimentally. The on-going development of shaped laser sources from the mid-infrared to the ultraviolet has lead to the control of a diversity of photophysical and photochemical phenomena, e.g., rovibrational and/or electronic state population transfer, photoisomerization. An important complement to these many experiments is a detailed understanding of the mechanism(s) leading to control. The proposed research will further develop and apply methods for examining laser control in polyatomic molecules. Applications will include photoisomerization and, in particular, photoswitchable proteins.**