Tunable Photochromism in the Robust Dithienylethene‐Containing Phospholes: Design,Synthesis, Characterization,Electrochemistry, Photophysics,and Photochromic Studies

A series of dithienylethene‐containing phosphole derivatives has been designed, synthesized and characterized. One of the compounds has been characterized by X‐ray crystallography. Upon photoexcitation, the compounds exhibit drastic color changes, ascribed to the reversible photochromic behavior. Their photochromic, photophysical and electrochemical properties have been studied. They show photochromic reactivities with high photocyclization quantum yields. Their photophysical and photochromic properties are found to be facilely tuned in this system by substitution at the phosphole backbone, as well as variation on the extent of π‐conjugation of the phosphole backbone. Some selected compounds have been demonstrated to exhibit photochromic properties in polymethylmethacrylate (PMMA) films.     

Of Twists and Curves: Electronics,Photophysics, and Upcoming Applications of Non-Planar Conjugated Organic Molecules

Non-planar conjugated organic molecules (NPCOMs) contain π-conjugation across their length and also exhibit asymmetry in their conformation. In other words, certain molecular fragments in NPCOMs are either twisted or curved out of planarity. This conformational asymmetry in NPCOMs leads to non-uniform charge-distribution across the molecule, with important photophysical and electronic consequences such as altered thermodynamic stability, chemical reactivity, as well as materials properties. Majorly, NPCOMs can be classified as having either Fused or Rotatable architectures. NPCOMs have been the focus of significant scientific attention in the recent past due to their exciting photophysical behavior that includes intramolecular charge-transfer (ICT), thermally activated delayed fluorescence (TADF) and long-lived charge-separated states. In addition, they also have many useful materials characteristics such as biradical character, semi-conductivity, dynamic conformations, and mechanochromism. As a result, rational design of NPCOMs and mapping their structure-property correlations has become imperative. Researchers have executed conformational changes in NPCOMs through a variety of external stimuli such as pH, temperature, anions-cations, solvent, electric potential, and mechanical force in order to tailor their photophysical, optoelectronic and magnetic properties. Converging to these points, this review highlights the lucrative electronic features, photophysical traits and upcoming applications of NPCOMs by a selective survey of the recent scientific literature.     

1,8-萘啶衍生物的结构、光物理性质及其应用

1,8-萘啶衍生物的刚性平面氮杂环结构使其具有丰富的光物理性质,因而在金属离子识别、配位化学等方面有着广泛的应用. 许多1,8-萘啶衍生物还具有独特的生理活性,并应用于临床治疗,这为该类化合物在生物医学领域中的研究和应用奠定了基础. 本文简要介绍了1,8-萘啶衍生物的结构特点及近期的研究进展.     

Molecular wires based on thienylethynylene: synthesis, photophysical properties, and excited-state lifetime

A series of pi-conjugated molecular wires based on thienylethynylene units have been developed to understand the effect of the molecular structures on their photophysical properties. The investigation of their photophysical properties indicates that the formation of aggregates at the ground state is effectively suppressed by the incorporation of truxene units. The excited-state lifetimes are observed to be biexponential for these molecular wires.     

Luminescent triarylborane-functionalized polystyrene: synthesis, photophysical characterization, and anion-binding studies

A new class of highly fluorescent triarylborane polymers has been prepared from trimethylsilyl-substituted polystyrene via a modular approach that involves selective polymer modification reactions with organometallic reagents. The photophysical properties, environmental stability, and the Lewis acidity of the boron sites have been tailored through modifications in the substitution pattern on boron. The photophysical properties are indicative of electronic communication between the chromophores attached to polystyrene, which has been exploited for the efficient probing of fluoride and cyanide in the micromolar concentration range.     

PHOTOPHYSICAL PROPERTIES OF NUCLEIC ACID COMPONENTS—1. THE PYRIMIDINES: THYMINE, URACIL, N, N-DIMETHYL DERIVATIVES AND THYMIDINE

Abstract— Low-temperature (and some room temperature) absorption and emission, fluorescence and phosphorescence, data including quantum yields and lifetimes have been obtained from the title pyrimidine bases as a function of the nature of the solvent environment. Modest vibrational resolution has been observed for the first time in the absorption spectra, particularly for thymine and uracil. The excitation spectra also show structure. The quantum yields of fluorescence (φ_F) and phosphorescence are independent of the excitation wavelength. Thymine, thymidine and uracil have profoundly different photophysical properties in polar-aprotic vs polar-protic solvents. The N, N-dimethyl substitution of thymine and uracil produces photophysical changes comparable to the solvent change for the unsubsti-tuted bases. The species involved in the emission processes is the keto (lactam) form. It is probable that ^1,3(n,π*) state(s) has(have) changed order relative to a lowest ¹(π,π*) state as a consequence of both the solvent change and N, N-dimethyl substitution. The lowest triplet state is assigned as ³(n π*). We propose that an important factor contributing to the previously reported excitation wavelength dependence of φ_F and φ_T1 (φ_isc) for nucleic-acid components is the equilibrium coexistence of H-bonded and non-H-bonded forms each having different photophysical properties. Consideration is given of the impact of the significantly different photophysical properties of nucleic-acid bases as a function of the nature of the solvent upon the photochemical properties.     

Donor–acceptor perylenediimide–ferrocene conjugates: synthesis,photophysical, and electrochemical properties

Donor–acceptor, perylenediimide–ferrocene conjugates have been synthesized by Suzuki, and Sonogashira coupling reactions. The photophysical and electrochemical properties of these conjugates are discussed. It has been shown that fluorescence as well as the electron affinity of the perylenediimide can be tuned by attaching the appropriate ferrocenyl derivatives.     

Aggregation induced colour change for phosphorescent iridium(III) complex-based anionic surfactants

We describe a new class of water soluble metallosurfactant molecules based on luminescent neutral iridium(III) complexes. The compounds possess an alkyl chain terminated with a negatively charged group, a sulphate. Due to their amphiphilic nature they assemble in aggregates in water and their photophysical properties, as well as the morphological characterization of the assemblies are presented. In particular, UV-Vis absorption, steady-state and time-resolved emission spectroscopy, dynamic light scattering and scanning electron microscopy techniques have been employed towards the analysis of the assemblies in different media. Comparison with the single components shows that the aggregates have very different photophysical properties. Importantly, the change in colour upon self-assembly is a remarkable feature which could be used for the design of probes which can change properties in different environments.     

Transition metal based supramolecular systems: synthesis, photophysics, photochemistry and their potential applications as luminescent anion chemosensors

This review describes our recent research results on several transition-metal based supramolecular systems. A number of self-assembly metallocyclophanes and cages have been prepared. We have found that the photophysical properties of these systems are highly dependent on the nature of the bridging ligands and that many of these metallocyclophanes and cages are capable of binding different guest molecules such as inorganic anions and a variety of aromatic compounds. Moreover, trinuclear (diimine) rhenium(I) tricarbonyl complexes linked by a stilbene-like ligand exhibit most interesting photoswitching features, where the luminescence from the complexes can be switched on and off by photoinduced ligand isomerization. In addition, a structurally simple and easily synthesized luminescent anion receptor has been recently developed and it displays outstanding sensitivity and selectivity toward anionic species. We also review the synthesis of two shape-persistent hexagonal phenylacetylenes and their use as ligands to synthesize dinuclear transition-metal complexes. The photophysical properties of both phenylacetylenic ligands and their corresponding metal complexes are summarized.     

Synthesis and Liquid Crystal Properties of Novel Oligothiophene Derivatives

Oligothiophenes with well defined structures have recently received a great deal of attention not only as modelcompounds for electrically conducting polythiophenes but also as a new class of functional π-electron systems. A variety of oligothiophenes have been synthesized, and their molecular and crystal structures, self ordering, electrochemical, photophysical, optical and electrical properties have been studied.     

B,B-Diporphyrinbenzyloxy-BODIPY dyes: synthesis and antenna effect

B,B-Diporphyrinbenzyloxy-BODIPY derivatives have been prepared in high yields, and the photophysical properties are reported. Singlet energy transfers from BODIPY to the porphyrin units have been analyzed.     

香豆素衍生物溶液的光谱和光物理行为

通过对一系列不同取代的香豆素化合物在不同溶剂中的光谱测定,研究了结构和溶剂极性对它们光物理行为的影响.发现了它们的光物理特征与其结构和多种溶剂极性参数间存在的一些关系,为进一步更好的利用这类化合物提供了重要依据.     

Emission wavelength prediction of a full-color-tunable fluorescent core skeleton, 9-aryl-1,2-dihydropyrrolo[3,4-b]indolizin-3-one

In this paper we report on a novel fluorescent core skeleton, 9-aryl-1,2-dihydropyrrolo[3,4-b]indolizin-3-one, which we named Seoul-Fluor, having tunable and predictable photophysical properties. Using a concise and practical one-pot synthetic procedure, a 68-member library of new fluorescent compounds was synthesized with diverse substituents. In Seoul-Fluor, the electronic characteristics of the substituents, as well as their positional changes, have a close correlation with their photophysical properties. The systematic perturbation of electronic densities on the specific positions of Seoul-Fluor, guided with the Hammett constant, allows emission wavelength tunability covering the full color range. On the basis of these observations and a computational analysis, we extracted a simple first-order correlation of photophysical properties with the theoretical calculation and accurately predicted the emission wavelength of Seoul-Fluors through the rational design. In this study, we clearly demonstrate that Seoul-Fluor can provide a powerful gateway for the generation of desired fluorescent probes without the need for a tiresome synthesis and trial-and-error process.     

Synthesis of Cyclometalated Platinum(II) Complex with an Alkynyl-Substituted Isocyanide Ligand,Its Structure and Photophysical Properties

The cyclometalated complex of platinum(II) [Pt(ppy)Cl(CNC6H4CCPh)] with phenylpyridine and [4-(2-phenylethynyl)phenyl]isocyanide ligands has been synthesized from the [Pt(ppy)Cl]2 dimer and CNC6H4CCPh isocyanide with 90% yield. The compound structure has been characterized using mass spectrometry, IR and NMR spectroscopy methods as well as single-crystal X-ray diffraction. The photophysical properties of the complex in a solid phase have been studied.     

Photochromic Dithienylethene‐Containing Boron(III) Ketoiminates: Modulation of Photo‐Responsive Behavior through Variation of Intramolecular Motion

A series of dithienylethene‐containing boron(III) ketoiminates, as well as their corresponding β‐ketoimine ligands, have been synthesized and characterized. The photophysical, electrochemical, and photochromic properties of the compounds have been studied. Photocyclization has been found to be suppressed upon introduction of a phenyl substituent on the nitrogen atom of the β‐ketoiminate core, whereas photochromism could be observed by replacement of the phenyl substituent with a bulky mesityl group. It is believed that the steric effect of the mesityl unit restricts molecular rotation, resulting in such a prominent difference in the photochromic properties.     

Toward new materials for organic electroluminescent devices: synthesis, structures, and properties of a series of 2,5-diaryl-3,4-diphenylsiloles

A series of 2,5-diaryl-3,4-diphenylsiloles, with various mono-substituted phenyl groups, extended pi-conjugated groups, and heteroaryl groups as aryl groups at the 2,5-positions, has been prepared by a one-pot synthesis from bis(phenylethynyl)silanes based on the intramolecular reductive cyclization followed by the palladium-catalyzed cross-coupling with aryl halides. Crystal structures and chemical reactivities toward the alkaline desilylation reactions have been studied on the 2,5-bis(p-mono-substituted phenyl)silole derivatives to elucidate the effects of the p-substituents. The UV-visible absorption and fluorescence spectra, and cyclic voltammetry of the 2,5-diarylsiloles have been systematically evaluated. Their photophysical properties as well as their electronic structures significantly depend on the nature of the 2,5-aryl groups.     

Developing luminescent silver nanodots for biological applications

Though creation and characterization of water soluble luminescent silver nanodots were achieved only in the past decade, a large variety of emitters in diverse scaffolds have been reported. Photophysical properties approach those of semiconductor quantum dots, but relatively small sizes are retained. Because of these properties, silver nanodots are finding ever-expanding roles as probes and biolabels. In this critical review we revisit the studies on silver nanodots in inert environments and in aqueous solutions. The recent advances detailing their chemical and physical properties of silver nanodots are highlighted with an effort to decipher the relations between their chemical/photophysical properties and their structures. The primary results about their biological applications are discussed here as well, especially relating to their chemical and photophysical behaviours in biological environments (216 references).     

Recent Advances in the Z/E Isomers of Tetraphenylethene Derivatives: Stereoselective Synthesis,AIE Mechanism,Photophysical Properties,and Application as Chemical Probes

Focused research on the Z/E isomers of tetraphenylethene (TPE) derivatives is scarce in comparison with the thousands of luminogens with AIE properties (AIEgens) that have been synthesized based on the TPE moiety. The similar chemical and physical properties of the Z/E isomers make them difficult to separate by using conventional chromatographic techniques. However, they can be isolated by introducing polar groups and the pure isomers exhibit very different photophysical properties, mechanochromism, and host–guest coordination, as well as assisting in deciphering the AIE mechanism. In this Minireview, we present an overview of the disagreement regarding the AIE mechanism between the restriction of intramolecular vibration and photoinduced Z/E isomerization. Then, we discuss the development of (Z)‐/(E)‐TPE derivatives, their use in host–guest detection, and their mechanoluminescence properties, with a focus on their photophysical characteristics. Finally, we explore the stereoselective synthesis of pure (Z)‐/(E)‐TPE derivatives.     

Synthesis, characterization and photochromic studies of spirooxazine-containing 2,2'-bipyridine ligands and their rhenium(I) tricarbonyl complexes

A series of spirooxazine-containing 2,2'-bipyridine ligands and their rhenium(i) tricarbonyl complexes has been designed and synthesized, and their photophysical, photochromic and electrochemical properties have been studied. The X-ray crystal structures of two of the complexes have been determined. Detailed studies showed that the emission properties of the complexes could readily be switched through photochromic reactions.     

Dendritic phthalocyanines: synthesis,photophysical properties,and aggregation behavior

This mini-account describes our recent effort to exploit dendritic phthalocyanines, focusing on their photophysical properties and aggregation behavior in water and in microheterogeneous media. Two series of dendritic phthalocyanines have been prepared. The ones with terminal ester functionalities are non-aggregated in common organic solvents, exhibiting an intramolecular singlet-singlet energy transfer from the excited aryl-containing dendrons to the phthalocyanine core. The other series contain terminal carboxylate groups of which the aggregation tendency in water decreases as the size of the dendron increases. The lower-generation analogues are susceptible to surfactants, in particular the cationic n-hexadecyltrimethylammonium bromide (CTAB), and poly(ethylene oxide) (PEO), which are very effective to disrupt the molecular aggregation of phthalocyanines. The interactions have been monitored by absorption and fluorescence spectroscopy together with laser light scattering. The photophysical properties of the dendrimer/PEO complexes have also been studied by transient spectroscopy. To cite this article: D.K.P. Ng, C. R. Chimie 6 (2003).