Tuning Photoswitchable Dual-Color Fluorescence from Core-Shell Polymer Nanoparticles

Core-shell polymeric nanoparticles (NPs) containing photoswitchable spiropyrans (SP) and spirooxazines (SO) within the cores were fabricated. Fluorescence photoswitching studies revealed that the substituent groups on the photochromic SP/SO structures exerted significant influence on the fluorescence photoswitching behaviors of the as-prepared polymeric NPs, such as the reversibly interchangeable fluorescence color and the photoswitching kinetics. The electron-releasing and electron-withdrawing abilities of the substituent groups are believed to play important roles in controlling the electron configuration of the photochromic component and therefore be responsible for the tunable dual-color photoswitching performance.     

Fluorescence Intensity Modulation in Photochromic Conjugated Polymer Systems

The ability to modulate fluorescence intensity with a light signal enables a variety of applications based on fluorescence imaging. One approach to fluorescence photomodulation involves using a photochromic moiety that responds to a light signal in conjunction with a nearby fluorophore. We employ conjugated polymers based on poly(p-phenylene vinylene) (PPV) as the fluorophore in photochrome-fluorophore systems for fluorescence modulation. Advantages of using conjugated polymers for this purpose include their intrinsic energy migration processes that enable amplified fluorescence quenching as well as their processability. Here we present examples of PPV-based photomodulation systems that employ photochromic dyes from three common photochromic families: azobenzenes, spironaphthoxazines, and diarylethenes. In all cases we observe reversible fluorescence quenching due to fluorescence resonance energy transfer to the photogenerated form of the photochrome. Examples of the photomodulation of photochromic PPV systems in organic solution, polymer films, and conjugated polymer nanoparticles are presented.     

Photoswitching Emission with Rhodamine Spiroamides for Super-resolution Fluorescence nanoscopies

Spatial resolution in far-field fluorescence microscopy is limited by diffraction to about 200 nm. With the aid of photoswitchable fluorophores, the diffraction barrier has been successfully overcome, allowing unprecedented resolution in the order of single biomolecules. The imaging process demands markers with strict and reliable control of the switching, to keep most of the markers in a non-emissive state most of the time and to bring a tiny number back to an emissive state, and detection at the single-molecule level. Herein, we describe the use of rhodamine spiroamides with unique photophysical properties as molecular probes for super-resolution techniques based on the localization of single emitters. This family of photochromic and fluorescent compounds fulfils the stringent requirements for such imaging methods; these compounds are robust and capable of enduring single-molecule detection in diverse environments. This has allowed meaningful images with resolution down to a few nanometres. Their design, synthesis and implementation is discussed along with imaging applications in material and life sciences.     

Molecules in Motion: From Sub-Nanoscale to Macroscale

Ruthenium polypyridine complexes comprising sulfoxide ligands show dramatic photochromic behavior based on phototriggered S→O and O→S isomerization. Quantum yields of isomerization can be large, indicating that the excited-state bond-breaking and bond-making reactions are efficient. Ultrafast transient absorption spectroscopy reveals both adiabatic and non-adiabatic isomerization mechanisms. Incorporation of these complexes within polymer matrices leads to macroscopic bending of the polymer in an example of a direct transduction of photonic energy to mechanical energy.     

柠檬酸诱导合成铯钨青铜及其近红外遮蔽性能

以钨酸钠和碳酸铯为原料,在水热条件下利用柠檬酸有机诱导合成出铯钨青铜（CsxWO3）粉体,并将其分散于聚乙烯醇（PVA）溶液中,在玻璃表面制备CsxWO3薄膜。用X射线衍射仪和能谱仪对CsxWO,粉体的结构和形貌进行了表征,借助紫外一可见分光光度计研究了CsxWO3粉体及薄膜的光吸收性能。结果表明：Cs0.32WO3粉体和薄膜为六方结构,与用同样工艺得到的WO3相比,CsxWO3粉体表现出强烈的近红外吸收性能,粉体吸光度高达1．96,其薄膜表现出良好的近红外遮蔽性能,近红外1100rim处的透光率与町见光区的最高透光率相比,下降了13％～18％;经过紫外光照射后,CsxWO3薄膜表现出良好的光致变色性能,且其近红外遮蔽性能进一步提高,特别是在柠檬酸浓度较高的前驱液中合成的CsxWO3,其薄膜近红外遮蔽性能提高的效果更为明显,近红外区1100nm处的透光率与可见光区的最高透光率相比,下降了26％。     

若干无机/有机复合光功能材料及相关器件研究进展

在无机基质中光学均匀掺杂有机光添生物质以获得复合光功能材料是近年来的研究热点,复合光功能材料的溶胶－凝胶低温合成技术为其在非线性光学、固态可调谐染料激光器、发光显示、光致变色、光化学烧孔等领域的应用提供了可能。本文对无机／有机复合光功能材料的制备技术、结构与性能的表征手段,及其作为发光、激光、波导、波分复用、光致变色器件在光通信中的应用等研究进展作了评述。     

Influence of polymer polarity on photochromic behavior of naphthodipyran doped in different polymeric matrixes

Photochromic polymer films were prepared by doping the naphthodipyran into different polymers such as Polyvinylpyrrolidone (PVP), styrene‐butadiene‐styrene (SBS) triblock copolymer, and polymethyl methacrylate (PMMA) at different concentrations. The kinetics of the photochromism/decoloration in the thin films was quantified by fitting biexponential equations to their photochromic decay curves after UV irradiation. The results show that the fastest decoloration process was in SBS, and the slowest one was in PVP. The DSC results indicate that T_g of polymeric matrix has no obvious effect on the decoloration rate of naphthodipyran. The decreasing order of the decoloration constant of naphthodipyran was consistent with increasing polarity of polymer matrixes as PVP > PMMA > SBS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

2-芳氧基-1,8-邻苯二甲酰基萘的合成及光致变色性

合成了3种2-芳氧基-1,8-邻苯二甲酰基萘类光致变色化合物,通过核磁共振谱、红外光谱、质谱和元素分析确定了结构.对产物进行了荧光光谱测定,3种光致变色化合物的荧光强度和Stoke位移都较大.用紫外-可见分光光度计对其在丙酮溶液中的光致变色行为进行了测定,3种光致变色化合物在300—600 nm范围内都具有一定的光致变色性能和较大的吸光系数.     

9＇-取代吲哚啉螺噁嗪衍生物的合成与光谱性质

将2个9’－羟基吲哚啉螺萘并噁嗪衍生物（Ia、Ib）,进一步以N,N’－二环己基碳二酰亚胺为脱水剂、4－二甲氨基吡啶为催化剂合成了2个9’－丙烯酰氧基吲哚啉螺萘并噁嗪衍生物（IIIa,IIIb）和2个9’－（α－呋喃丙烯酰氧基）吲哚啉螺萘并噁嗪衍生物（Va,Vb）。通过元素分析、^1HNMR和IR对产物的结构进行了表征。将化合物Ⅲa的乙醇溶液浸渍在脱脂棉上,经太阳光照射由无色变为蓝色;当脱脂棉移至阴暗处后,蓝色慢慢变淡消失。光致变色过程循环50次无异常发生,显示出良好的光致变色性能。     

偶氮聚碳酸酯的制备与性能研究

以对氨基苯甲酸、亚硝酸钠和苯酚为原料,通过重氮偶合反应合成了对羟基偶氮苯甲酸,并用红外光谱和核磁共振对所合成的对羟基偶氮苯甲酸的结构进行了表征。将羟基偶氮苯甲酸与聚碳酸酯进行熔融混合并进行酯交换反应,制备了偶氮聚碳酸酯。通过光学性能和力学性能研究发现,所制备的偶氮聚碳酸酯具有优异的光致变色性能和透明性,力学性能与聚碳酸酯相当。