Illuminating Excited-State Intramolecular Proton Transfer of a Fungi-Derived Red Pigment for Sustainable Functional Materials
Illuminating Excited-State Intramolecular Proton Transfer of a Fungi-Derived Red Pigment for Sustainable Functional Materials
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DOI：
10.1021/acs.jpcc.1c09773
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发表时间：
2021-12
期刊：
影响因子：
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通讯作者：
Taylor D. Krueger;J. Solaris;Longteng Tang;Liangdong Zhu;Carter Webber;R. V. Van Court;S. Robinson;O. Ostroverkhova;Chong Fang
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文献类型：
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作者：
Taylor D. Krueger;J. Solaris;Longteng Tang;Liangdong Zhu;Carter Webber;R. V. Van Court;S. Robinson;O. Ostroverkhova;Chong Fang
质子转移是光敏有机分子从光稳定性到能量转移等功能性质的重要组成部分。对于一种由木材分解真菌Scytalidium cuboideum分泌的有机色素，尽管早在几十年前就被发现，但人们对Draconin Red知之甚少。稳态和时间分辨光谱技术以及量子计算，两个互变异构体的血竭素红与不同方向的羟基被发现，包括大部分的平衡人口。这些互变异构体可能是荧光和非荧光针状晶体中的主要物种的基础，前者显示出波导特性。飞秒瞬态吸收测量揭示了一个动态平衡，由于激发态分子内质子转移（ESIPT）的两个互变异构体之间的更快（<120 fs）和更慢（<750 fs）的时间尺度，通过计算扫描两个不等价的ESIPT坐标补充。地面和激发态飞秒受激拉曼光谱（FSRS）证实了存在的两种互变异构体在溶液中的振动标记带的光激发后的关键频率偏移，跟踪初始超快单向互变异构化。我们设想的高度对称的红色颜料的合理设计，结合电子给和/或吸电子基团，以提高电子和光子性能的这种天然衍生的小分子从溶液到固态。
Proton transfer is an important player that contributes to functional properties of light-sensitive organic molecules from photostability to energy transfer. For an organic pigment secreted by the wood-spalting fungusScytalidium cuboideum, little is known about Draconin Red despite its discovery decades earlier. With steady-state and time-resolved spectroscopic techniques as well as quantum calculations, two tautomers of Draconin Red with different orientations of hydroxy groups were found to comprise most of the equilibrium population. These tautomers may underlie major species in fluorescent and nonfluorescent needle-like crystals, the former showing waveguide properties. Femtosecond transient absorption measurements revealed a dynamic equilibrium due to excited-state intramolecular proton transfer (ESIPT) between the two tautomers on faster (<120 fs) and slower (∼750 fs) time scales, supplemented by computationally scanning two nonequivalent ESIPT coordinates. Ground and excited-state femtosecond stimulated Raman spectroscopy (FSRS) confirmed the presence of both tautomers in solution with key frequency shifts of vibrational marker bands upon photoexcitation, tracking an initial ultrafast unidirectional tautomerization. We envision the rational design of the highly symmetric red pigment by incorporation of electron donating and/or withdrawing groups to elevate the electronic and photonic performance of this naturally derived small molecule going from solution to the solid state.