光致变色冠醚部花菁染料的合成及其逆光致变色性

作者用含冠醚结构单元的2-甲基-苯并噻唑季铵盐与取代水物醛缩合得到了五个光致变色冠醚部化菁化合物。这些新的冠醚化合物具有逆光致变色性质, 较稳定的结构是开环部花菁式。     

Solid-state photochromism of chromenes: enhanced photocoloration and observation of unstable colored species at low temperatures

Solid-state photochromism of benzopyrans and naphthopyrans (chromenes) was investigated in the temperature range between 300 and 80 K. Variable-temperature diffuse reflectance spectroscopy of microcrystalline powders showed that the extent of photocoloration was greatly enhanced at low temperatures. All the chromenes examined exhibited solid-state photochromism at low temperatures, even when they showed little or no photocoloration at room temperature. The solid-state photochromic properties of the chromenes were quite similar to those reported for analogous photochromic compounds of spiropyrans and spirooxazines, which indicates that these classes of compounds are generally photochromic even in the solid state. Photobleaching reactions of the colored merocyanine forms proceeded at low temperatures through the formation of a colorless intermediate, instead of directly resuming the original closed form. In addition to two stable planar merocyanine forms, which are usually observed in the photochromic reactions in solution, photoreactions at low temperatures allowed us to observe unstable colored species, which were tentatively assigned as nonplanar cisoid forms, and were stabilized in the solid state at low temperatures.     

螺吡喃化合物在分析化学中的应用

螺吡喃作为一种有机光致变色化合物,能够发生无色闭环体螺吡喃与有色开环体部花菁之间可逆的结构异构化,由于具有特殊的分子识别能力和信号传导功能,已经成为分子探针领域极具吸引力的主体分子之一。螺吡喃不仅被广泛应用于光电材料领域作为分子器件,而且作为传感器广泛应用于分析化学领域。研究者们设计了多种具有不同结构的螺吡喃分子,将其应用于光化学和电化学传感领域。本文系统综述了螺吡喃化合物在分析化学领域的研究进展,包括螺吡喃作为光学探针在分子识别(对金属离子、阴离子及有机分子的定性及定量分析)方面的应用,以及螺吡喃在电化学免疫传感器中的应用。     

Crown-containing spironaphthoxazines and spiropyrans. 3. Synthesis and investigation of the merocyanine form of crown-containing spirobenzothiazolinonaphthoxazine

A method for the synthesis of the spirobenzothiazolinonaphthoxazine, stable in the merocyanine form and containing a crown-ether fragment was developed. The complexing properties of the prepared merocyanine compound and the spectroscopic and photochromic characteristics of its complexes with alkaline earth metal cations were studied by NMR and UV spectroscopy. The results were analyzed using quantum-chemical calculations. The addition of alkaline earth metal perchlorates to a solution of a crown ether-containing merocyanine dye in MeCN results in the coordination of metal cations to two binding centers, namely, the crown-ether fragment and the merocyanine oxygen atom. This gives rise to two types of complexes, which differ substantially in their structurally. The complexation induces changes in the UV spectra and influences on the photochromic behavior of the prepared compound.     

Synthesis of novel chalcone derivatives and their stabilization effect of spiropyran in PMMA films

Three novel bis-chalcone derivatives with different alkyldioxy spacers were synthesized and dispersed into polymethyl methacrylate(PMMA) chloroform solution with 6-nitro-1’-ethyl-3’,3’-dimethylspiro-2H-1-benzopyran-2,2’-indoline(ESP) to prepare photochromic PMMA films in a facile way.After irradiation with 365 nm UV light,the photocrosslinking reaction between chalcone units was proved to retard the dccolorization of merocyanine form of the photochromic spiropyran effectively,as results of the steric hindrance produced by photocycloaddition of chalcone groups.It has been found that the bis-chalcone molecule with the shortest spacer has the most effective stabilizing effect on retardation of decoloration of spiropyran.     

Pulsed laser photolysis of spiropyrans in the presence of acids

Conclusions Intermediate unstable trans isomers of the merocyanine species participate in the protolytic reaction of spiropyrans. A scheme for the photochromic transformations of spiropyrans in the presence of an acid was proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2698–2703, December, 1985.     

Synthesis of functionalized spiropyran and spirooxazine derivatives and their photochromic properties

Three series of functionalized spiropyrans and spirooxazines derivatives were synthesized and their photochromic properties were investigated in particular regard to the fatigue resistance, the lifetime of the colored merocyanine form and the interaction of the colored form molecule. (1) Spiropyrans 5 and spironaphthooxazines 6 having an antioxidant group as a pendant exhibited higher fatigue resistance than that of the parent spiro compounds in solution. In particular, spiropyrans 5 showed higher resistance than parent compound 1 in the presence of an equimolar amount of the corresponding antioxidant. (2) bis-Spironaphthooxazines 8a–8i and 10 connected through a phosphoryl group exhibited higher fatigue resistance and longer lifetime of the colored merocyanine form than those of the parent spirooxazine 7. (3) Symmetrical bis-spiro photochromic compounds 15 and 16 and unsymmetrical bis-spiro compounds 13, 14 and 17 were synthesized. The bis-spiro photochromic compounds were found to undergo intramolecular interaction between the colored merocyanine forms.     

A semiclassical molecular dynamics of the photochromic ring-opening reaction of spiropyran

The photochromic ring-opening reaction of spiropyran(SP) has been investigated by a realistic semiclassical dynamics simulation,accompanied by SA3-CASSCF(12 10)/MS-CASPT2 potential energy curves(PECs) of S0–S2.The main simulation results show the dominate pathway corresponds to the ringopening process of trans-SP to form the most stable merocyanine(MC) product.These findings provide more important complementarity for interpreting experimental observations.     

Synthesis and spectral characteristics of photochromic 6- and 8-phenyl- substituted indoline spirochromenes

Two photochromic indoline spirochromenes were synthesized. The introduction of a phenyl group into the 6 or 8 position causes a bathochromic shift of the bands in the electronic absorption spectrum of the merocyanine form.     

Photochromic polypeptides

Two photochromic polypeptides were synthesized by reaction of 1-(4-iodobutyl)-3,3- dimethylindolindolino-6′-nitrobenzospiropyran with poly-L -tyrosine; their molar contents on photochromic units were 27.3 and 44.7%. The spectra of the photo-induced merocyanines and their decoloration kinetics were compared with these of the monomeric model compound, obtained by reaction of the same N-(4-iodobutyl)-indolinospiropyran derivative with N-acetyltyrosine methyl ester. Different types of solvents have been examined, mainly dimethylformamide and pyridine, acetone and tetrahydrofuran, and methanol and ethylene glycol. The polypeptides showed a much less pronounced solvatochromism than their model; on the other hand, their absorption spectra presented two absorption maxima instead of one for the model. These differences in photochromic behavior were interpreted on the basis of the solvatation of the polymeric chain. Inverse photochromism was observed for polypeptide P₂ as well as for the model in ethylene glycol solution; this effect is due to a higher merocyanine content at the thermal equilibrium spiropyran ? merocyanine in high polar solvent.     

Photoswitched singlet energy transfer in a porphyrin-spiropyran dyad.

A photochromic nitrospiropyran moiety (Sp) has been covalently linked to a zinc (PZn) and to a free-base (P(H2)) porphyrin. In the resulting dyads (P(Zn)-Sp(c) and P(H2)-Sp(c)), the porphyrin first excited singlet states are unperturbed by the closed form of the attached spiropyran. Excitation of the spiropyran moiety of either dyad in the near-UV region results in ring opening to a merocyanine form (P-Sp(o)) that absorbs at 600 nm. The open form re-closes thermally in 2-methyltetrahydrofuran with a time constant of 20 s, or following irradiation into the 600 nm band. Excitation of the zinc porphyrin moiety in the merocyanine form of the dyad yields 1PZn-Sp(o). The lifetime of the zinc porphyrin excited state is reduced from its usual value of 1.8 ns to 130 ps by singlet-singlet energy transfer to the merocyanine moiety to give PZn-1Sp(o). The quantum yield of energy transfer is 0.93. Quenching is also observed in the free base dyad, where 1P(H2)-Sp(o) and P(H2)-1Sp(o) exchange singlet excitation energy. This photoswitchable quenching phenomenon provides light-activated control of the porphyrin excited states, and consequently control of any subsequent energy or electron-transfer processes that might be initiated by these excited states in more complex molecular photonic or optoelectronic devices.     

Photochromic fulgides and spirooxazines: mechanism and substituent effect on photoreactions

Molecular design, synthesis and photochromic properties of spirooxazines and fulgides are described. In the case of fulgides, the change of the substituents may lead to different photochromic properties and different photoreactions of the kind of compounds. In photochromic process of pyrryl-substituted fulgides, the excited singlet state is the mam species, but the excited triplet state is also involved. However, no excited triplet state has been observed in cyclization of aryl-substituted fulgides. In the case of spirooxazines, the substituents at 2'-position have great effect on the formation of photoproduct and on the mechanism of photoreaction. The increase of steric hindrance of the 2'-position substituent gives rise to the decrease of the quantum yield for the formation of photochromic merocyanine (PMC) and the increase of the relative quantum yield for the charge separated twist intermediate (CT).     

Switching Properties of a Spiropyran–Cucurbit[7]uril Supramolecular Assembly: Usefulness of the Anchor Approach

A nitrospiropyran, which was modified with a cadaverine‐derived anchor, was investigated with respect to its thermally induced isomerizations, hydrolytic stability of the merocyanine form, and photochromic ring closure. The host–guest complexation of the anchor by the cucurbit[7]uril macrocycle, evidenced by absorption titration, NMR spectroscopy, and electrospray ionization mass spectrometry, produced significant improvements of the switching properties of the photochrome: 1) appearance of the merocyanine form about 70 times faster, 2) practically unlimited hydrolytic stability of the merocyanine (two and a half days without any measureable decay), and 3) fast, clean, and fatigue‐resistant photoinduced ring closure back to the spiro form. The importance of an adequate molecular design of the anchor was demonstrated by including control experiments with spiropyrans with a shorter linker or without such structural asset.     

Local molecular dynamics of poly(ethylene glycol) dimethacrylate synthesized in the presence of branched poly(methyl methacrylate): a photochromic probe study

The local molecular dynamics and morphology of poly(ethylene glycol) dimethacrylate networks synthesized in the presence of 0–40% branched poly(methyl methacrylate) were studied using a photochromic probe (6-nitrospiropyran). The change in the free volume of the polymer in the vicinity of the photochromic probe was monitored by the rate of dark bleaching of merocyanine (colored form of 6-nitrospiropyran). The local free volume and the mobility of the polymer chain fragments decrease as the conversion of C=C bonds and the content of branched poly(methyl methacrylate) in the polymer increase.     

Detailed investigation on a negative photochromic spiropyran

The negative photochromic properties of a spiropyran are investigated in various solvents and in solutions of different acidity. The results indicate that the polarity of the solvent has a prominent effect on λ_max of the coloured merocyanine form (MC), whereas its effects on λ_max of the closed form (SP) and on the coloration rates after visible bleaching are very weak. From the effect of acid concentration on the coloration rates the pK_a of the cis intermediate Y in the coloration process is determined to be about 1.1 lower than that of the protonated merocyanine (MCH⁺). The structures and configurations of MC, SP, MCH⁺ and Y are assigned via their ¹H NMR spectra.     

Selective Acceleration of the Protonated Merocyanine‐Spiropyran Photochromic Transformation by Inclusion in Cucurbit[7]uril

The effect of cucurbit[7]uril (CB7) on the spiropyran‐merocyanine photochromic interconversion was studied in acidic and alkaline aqueous solutions. The merocyanine (MC) isomer was found to be the thermodynamically most stable form both in water and in the presence of CB7. A preferential binding of the protonated merocyanine (MCH⁺) to CB7 was observed with an equilibrium constant of 7.4 × 10⁴ m ^?1, and the complex formation led to significant diminution of acidity of the guest. The photoinduced transformation of MCH⁺ to the spiropyran isomer was accelerated 2.3‐fold upon addition of CB7, whereas the rates of the other photochromic processes were not affected. The partial inclusion of MCH⁺ in CB7 led to dual fluorescence due to the incomplete deprotonation in the singlet‐excited state.     

1-octadecyl- and 3,3-diphenyl-substituted photochromic indolinospirochromenes

A number of photochromic indolinospirochromenes that contain an octadecyl substituent in the 1 position were synthesized. The introduction of an octadecyl group in place of a methyl group increases the stability of the merocyanine form in solution but does not change its spectral characteristics. On the other hand, the introduction of phenyl groups in place of methyl groups in the 3 position does not change the stability of the merocyanine but gives rise to a bathochromic shift of the long-wave absorption band.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 51–54, January, 1980.     

Synthesis of 1, 3 -dimethyl-3-phenylspiro [indoline —2,2′-(2′H-l-benzopyran)]s and an investigation of the electronic absorption spectra of their merocyanine forms

The synthesis of photochromic indoline spiropyrans containing a phenyl substituent in position 3 has been effected. The electronic absorption spectra of the colored forms of the spiropyrans obtained reveal the properties typical for merocyanine dyes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1209–1211, September, 1973.     

Synthesis and photochromism of spirobenzopyran derivatives bearing an oxymethylcrown ether moiety: metal ion-induced switching between positive and negative photochromisms

Spirobenzopyran derivatives carrying an oxymethylcrown ether moiety were synthesized, and their photochromism was studied in the presence of various metal ions in acetonitrile. The metal ion complexing ability of the crown ether moiety in crowned spirobenzopyrans affects both thermal isomerization and photoisomerization of their spirobenzopyran moiety to a great extent. When the interaction of the crown ether moiety with a metal ion was strong enough to cause thermal isomerization of the spirobenzopyran moiety to its corresponding merocyanine form and to suppress UV-induced isomerization to the merocyanine form, a negative photochromism appears. On the other hand, a relatively weak interaction of the crown ether moiety with a metal ion affords a positive photochromism. This phenomenon enables us to switch the photochromic behavior between positive and negative photochromisms.     

Photo- and thermochromic spirans. 35.* Synthesis and photochromic properties of spiro[indoline-2,3′-pyrano[3,2-f]quinolines] and their cationic derivatives

New photochromic spiropyranoquinolines and their cationic derivatives have been synthesized. Quaternization of the quinoline fragment leads to significant enhancement of the thermal stability of the merocyanine isomers of these cationic spiropyrans.