新型以若丹明染料为母体的三发色团化合物的荧光性能

若丹明染料作为一种重要的激光染料,它们具有较高的荧光量子效率。这类染料在紫外区的吸收是相当小的,于是,当它们被使用在横向泵浦激光装置上时,就需要相当高的染料浓度,这样才能有效地吸收紫外泵浦光(如XeCI激光器,308 nm)。问题是,这类染料的发射光谱与其吸收光谱的低能量部分有重叠,亦即它门的Stokes位移较小,并且由于染料的荧光量子效率通常小于100,以致使一部分染料的激发辐射被基态染料分子再吸收,从而导致激发辐射的损失。与此同时,为了有效吸收泵浦光能量,染料的浓度通常很高,这样,激发辐射损失就会相当大。     

Photo-stability of yellow-green emitting 1,8-naphthalimides containing built-in s-triazine UV absorber and HALS fragments and their acrylonitrile copolymers

Two novel 1,8-naphthalimide dyes, containing active fragments of both 2-(2-hydroxyphenyl)-1,3,5-triazine UV absorber and 2,2,6,6-tetramethylpiperidine radical scavenger as well as a polymerisable allyl group, were designed as multifunctional yellow-green emitting fluorophores capable simultaneously of chemically fluorescent dyeing and photo-stabilisation of polymers. Their basic photo-physical characteristics have been determined and are discussed. It was shown that combination of different structural units in the 1,8-naphthalimide molecule does not result in their interaction through intramolecular fluorescence quenching due to an electronic energy transfer. The ability of the combined dyes to copolymerise with acrylonitrile was demonstrated as polyacrylonitriles stable to solvents and with an intense colour and fluorescence were obtained. Photo-degradation of the new fluorophores and their influence on the photo-stability of the coloured copolymers have been studied and compared to other similar fluorescent dyes, not containing either UV absorber or hindered amine fragment in their molecules as well as not containing both of them. Novel fluorophores showed the best photo-stability in both solution and polymer. A significant photo-stabilising effect towards photo-destruction of polyacrylonitrile was found, which might be caused by a possible “synergism” of two stabiliser fragments differing in their action.     

Photostability of novel copolymers functionalized with laser dyes based on modified rhodamine 6G and 1,8-naphthalimide

Modified rhodamine 6G molecules (Rh-Al or Rh-Aln) with polymerizable double bonds had been copolymerized with 1,8-naphthalimide derivatives. In copolymers PRNAM, naphthalimide moieties are connected to rhodamine moieties at nitrogen atom of rhodamine moiety, and in copolymers PRNM naphthalimide moieties are connected to rhodamine moieties at ester group of rhodamine moiety. We report on their photostability in liquid solution and in solid film. The photodegradation kinetics of novel copolymers functionalized with laser dyes based on modified rhodamine 6G and 1,8-naphthalimide has been studied by UV-VIS absorption spectroscopy. The results show that the rates of the photofading reactions of these novel copolymers follow quasi-first-order. The photostability of the copolymers functionalized with laser dyes in solid films is better than that in solutions. The different type of the copolymer shows the different photostability.     

Synthesis and characterization of 1,8-naphthalimide with [6]helicene skeleton

A 1,8-naphthalimide with [6]helicene derivative scaffold has been designed and synthesized. The (P)- and (M)-enantiomers of the [6]helicene derivative were resolved by HPLC on a chiral column. The single crystal of the [6]helicene derivative exhibits an intermolecular interactions of the 1,8-naphthalimide units.     

New green fluorescent polymer sensors for metal cations and protons

A new 4-(N-methylpiperazine)-N-allyl-1,8-naphthalimide with intense yellow-green fluorescence has been synthesized. Then it has been copolymerized with styrene and methylmetacrylate. The photophysical characteristics of the fluorescent dye and its copolymers (poly(St-co-NI) and poly(MAA-co-NI)) have been determined viewing their sensor properties for protons and transition metal cations (Cu²⁺, Fe³⁺ and Zn²⁺). Fluorescence enhancement is the photophysical response of the 4-(N-methylpiperazine)-N-allyl-1,8-naphthalimide to the presence of metal cations and protons, while fluorescence quenching is observed for both copolymers.     

New copolymer gels based on <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylacrylamide and crown-containing allyl derivative of 1,8-naphthalimide as optical sensors for metal cations in an organic medium

New copolymer gels bases on N,N-dimethylacrylamide and a crown-containing allyl derivative of 1,8-naphthalimide showing intense visible fluorescence have been prepared. The effect of metal cations on the optical properties of the fluorescent monomer and its copolymer gels has been studied. These gels have been found to exhibit optical response selectivity with respect to binding of alkaline-earth metals in an acetonitrile medium.     

Design and synthesis of core and peripherally functionalized with 1,8-naphthalimide units fluorescent PAMAM dendron as light harvesting antenna

This paper reports on the design, synthesis and spectral characteristics of a novel PAMAM dendron (7), core and peripherally functionalized with 1,8-naphthalimide fluorophores. The novel compound 7 was configured as light harvesting antenna where the system surface is functionalized with “donor” dyes (blue emitting 1,8-naphthalimides) that are capable of absorbing light and efficiently transferring the energy to a single “acceptor” dye (yellow-green emitting 1,8-naphthalimide) in the focal point of the dendron. The overlap between the emission of the donor and the absorbance of the acceptor was more than 95%. As a result of the energy transfer, the blue emission intensity of the periphery in the donor–acceptor system was decreased with 93%, while the yellow-green core fluorescence enhancement (λ_ex = 360 nm) of the system was more than 26 times with respect to the fluorescence intensity of the comparative yellow-green emitting 1,8-naphthalimide. This indicates efficient energy transfer between the donor and acceptor dye fragments and that the novel compound 7 would be able to act as a highly efficient light harvesting antenna.     

Photodegradation of poly(amidoamine) dendrimers peripherally modified with 1,8-naphthalimide units

This paper presents the photophysical and photochemical characteristics of four new poly(amidoamine) dendrimers of zero and second generation whose periphery has been modified with 1,8-naphthalimide units. Nitro- and allylamino groups have been used as substitutents at the C-4 position of the 1,8-naphthalimide fluorophores. The discussion is focused on the photodegradation of the dendrimers in N,N-dimethylformamide and dioxan solutions. Investigations have shown that the photodegradation of the dendrimers with 4-nitro substituted 1,8-naphthalimide proceed with yellow colour development in the solvent while no colour changes followed the same process in dendrimers with allylamino group substituent. The results also show that the photostability of the dendrimers depends on their generation.     

Synthesis and near-infrared characteristics of novel perylene bisimide dyes bay-functionalized with naphthalimide chromophores

Novel perylene bisimide dyes bay-functionalized with naphthalimide chromophores have been prepared conveniently by coupling of 1,8-naphthalimide and dibromoperylene bisimides. Their optical properties were investigated by UV-vis and fluorescence spectroscopy. The absorption spectra of these compounds showed wide spectral responses from 300 to 700 nm,which would be potentials for application as organic solar cells.     

A "green" route to perylene dyes: direct coupling reactions of 1,8-naphthalimide and related compounds under mild conditions using a "new" base complex reagent, t-BuOK/DBN.

The direct coupling reactions of 1,8-naphthalimide compounds efficiently occurred at 130 or 170 degrees C without the intervention of the leuco form dyes in the presence of base complex reagent, t-BuOK/1,5-diazabicyclo[4.3.0]non-5-ene (DBN), to give the corresponding perylene dyes in good yields with > 95% purities. A possible mechanistic speculation for these oxidative coupling reactions is briefly discussed.     

新型双发色团固体激光染料薄膜的光稳定性研究

利用UV-Vis吸收光谱仪和光化学反应器研究了新型双发色团固体激光染料薄膜的光降解动力学.研究结果表明:双发色团固体激光染料薄膜的光褪色反应遵循假一级动力学衰减.在PRNAM系列共聚物(N-烯丙基-若丹明1、N-[(2-丙烯酸基)乙基]-1,8-萘酰亚胺和甲基丙烯酸甲酯的共聚物)中萘酰亚胺基团通过聚合物碳链与若丹明基团的氮原子相连;而在PRNM系列共聚物(若丹明1的烯丙基酯、N-[(2-丙烯酸基)乙基]-1,8-萘酰亚胺和甲基丙烯酸甲酯的共聚物)中则是与若丹明基团的酯基相连.PRNAM系列共聚物的光稳定性优于PRNM和PRM(若丹明1的烯丙基酯和甲基丙烯酸甲酯的共聚物)系列的光稳定性.     

Structural organization of a {ruthenium[tris(bipyridyl)]} complex by strong π–π stacking of a tethered 1,8-naphthalimide synthon: Impact on electrochemical and spectral properties

The new ligand N-(5-methyl-2,2′-bipyridyl)-1,8-naphthalimide has been prepared by the reaction of 1,8-naphthalimide, 5-(bromomethyl)-2,2′-bipyridine and potassium carbonate in refluxing acetone. Reaction of this ligand and bis(bipyridyl)ruthenium(II) dichloride in refluxing ethanol followed by anion exchange with ammonium hexafluorophosphate produces {ruthenium[bis(bipyridyl)][N-(5-methyl-2,2′-bipyridyl)-1,8-naphthalimide]}(PF₆)₂ (1). In both the solid state (X-ray analysis) and in solution (shown by PGSE-NMR analysis), the 1,8-naphthalimide synthon organizes the cationic metal units into dimers with a strong, directionally oriented (head to tail) π–π stacking interaction. UV–VIS, fluorescence spectroscopy and electrochemical studies indicate that even with the strong interactions of the 1,8-naphthalimide groups, it does not have a significant influence on the properties of the [Ru(bipy)₃]²⁺ core.     

New trends of molecular probes based on the fluorophore4-amino-1,8-naphthalimide

4-Amino-1,8-naphthalimide(ANI) represents a valuable fluorophore from which a large number of probes have been derived in order to meet the requirements from the fields of biological sensing and imaging. In this review, the major progresses of ANI-based fluorescent probes in the past decade have been highlighted and categorized into three trends. The future development of ANI probes is also expected. This review provides a great deal of references and illuminating comments which will be helpful for the researchers designing and using fluorescent probes.     

Synthesis,crystal structures,and biological properties of a new naphthalimide Schiff base and its copper(II) complex

A new naphthalimide Schiff base N-allylamine-4-(ethylenediamine-3-methoxysalicylidene)-1,8-naphthalimide (HL) and its copper(II) complex {N-allylamine-4-(ethylenediamine-3-methoxysalicylidene)-1,8-naphthalimide copper(II)} (CuL₂) have been synthesized and characterized. The crystal structure of CuL₂ has been determined by X-ray single crystal diffraction. The central Cu(II) ion is four-coordinate with an N₂O₂ donor set which is afforded by two L ligands, forming a slightly distorted square planar geometry. The interactions of HL and CuL₂ with calf thymus DNA were investigated using electronic absorption titration, fluorescence titration, and viscosity measurements. The results indicate that free HL and CuL₂ bind to DNA in an intercalation mode, and their binding affinity for DNA takes the order CuL₂ > HL. Moreover, the antioxidant assay in vitro also shows that HL and CuL₂ possess significant antioxidant activities and CuL₂ is more effective than free HL.     

New trends of molecular probes based on the fluorophore 4-amino-1,8-naphthalimide

4-Amino-1,8-naphthalimide (ANI) is one of the popular fluorophores for the constructions of various probes. In this review, the major progresses of ANI probes in the past decade have been highlighted and categorized into three trends. The future development of ANI probes has been expected, too.     

Design and Synthesis of a Highly Stable Six-hydrogen-bonded Self-assembly Yellowish Green Electroluminescent Molecular Duplex

Since the first fabrication of thin-layer organic electroluminescent(OEL)device in1987by C.W.Tang et al1.,OEL materials had been of ever increasing interest2,3.While up to now,full-color display has been commercialized with small molecules having different structures.In general,host-dopant systems are often employed in RGB OLEDs.This procedure,however,would lead to relatively poor performance for OEL devices,because of the easy aggregation and crystallization of the dopants,which would…     

Anchoring of 1,8-naphthalimide derivative into mesoporous MCM-41 molecular sieves

The fluorescent dye molecules, 4-piperidine-1,8-naphthalimide, were successfully fixed into the amino modified pore channel of mesoporous MCM-41 type materials by in situ reaction of 4-piperidinyl-1,8-naphthalic anhydride with the amino group. The formation of amide bonds on the pore surface was verified by infrared spectra. The maximum fluorescence emission peak of this hybrid material has a red shift of 13 nm compared to that of a naphthalimide derivative in ethanol solution. Moreover, the fluorescence intensity of dye molecules grafted into Ce-doped MCM-41 is higher than that in pure silica MCM-41. This phenomenon is attributed to the inhibited internal electron transfer from piperidine to naphthalimide groups by Ce⁴⁺, thus improving the fluorescence intensity of the naphthalimide group. The unique fluorescence behavior of the 1,8-naphthalimide derivative doped hybrid mesoporous material makes it a good candidate for the metal ions microdetection.     

Design and Synthesis of a Ratiometric Fluorescent Chemosensor for Cu(II) with a Fluorophore Hybridization Approach

A new ratiometric fluorescent sensor for Cu(2+), WLN, has been developed via integrating a 1,8-naphthalimide fluorophore with 8-aminoquinoline. WLN exhibits a highly selective ratiometric response to Cu(2+) over other transition metal ions in aqueous media. Moreover, its practical ratiometric imaging ability for intracellular Cu(2+) has been confirmed in human breast adenocarcinoma cells (MCF-7 cells) using a confocal microscope.     

Selective detection of mercury(II) and methylmercury(II) via coordination-induced emission of a small-molecule probe

Mercury is one of the major toxic pollutants and has many adverse effects on human health. The main mercury species in the environment or in living organisms are inorganic mercuric ion (Hg²⁺) and organic methylmercury (CH3Hg+). Detection of the two mercury ions is a particularly active topic in the molecular sensing field during the past decade. However, efficient sensors that can sensitively detect and discriminate the two species are rare. In this work, we adopt the concept of restriction of intramolecular rotations which is the basis of aggregation induced emission, and design a molecular probe with pyridyl group as the chelating unit and 1,8-naphthalimide as the fluorescent unit for the detection of both Hg²⁺ and CH₃Hg⁺. When the probe is free in solution, it exhibits weak fluorescence because free intramolecular rotations of the 1,8-naphthalimide moieties non-radiatively annihilate its excited state. However, upon coordination with Hg²⁺ or CH₃Hg⁺, the rotation of 1,8-naphthalimide moieties would be restricted due to the chelation between 1,8-naphthalimide and Hg²⁺ or CH₃Hg⁺, leading to significantly enhanced fluorescent emission. The response induced by Hg²⁺ is much stronger than CH₃Hg⁺; but for specific detection of CH₃Hg⁺, we introduced a T-rich DNA fragment which could completely mask Hg²⁺ in solution. Furthermore, we have employed the sensor for confocal imaging of Hg²⁺ and CH₃Hg⁺in immobilized cells. We expect the probe design tactics can be generally useful for sensing many other analytes.     

FRET-based sensor for imaging chromium(III) in living cells

On the basis of fluorescent resonance energy transfer from 1,8-naphthalimide to rhodamine, a fluorophore dyad (FD8) containing rhodamine and a naphthalimide moiety was synthesized as a Cr3+-selective fluorescent probe for monitoring Cr3+ in living cells with ratiometric fluorescent methods.