Preparation, characterization and photocatalytic properties of InVO4 nanopowder and InVO4–TiO2 nanocomposite toward degradation of azo dyes and formaldehyde under visible light and ultrasonic irradiation

In this study, photocatalytic activity of InVO₄ and InVO₄–TiO₂ nanoparticles in the degradation of aqueous solutions of industrial textile azo dyes such as Solophenyl Red 3BL, Coperoxon Nevy Blue RL and Black Nilusun 2BC (abbreviated as SR 3BL, CNB RL and BN 2BC, respectively) and also formaldehyde (abbreviated as FAD) under visible light and ultrasonic irradiations has been compared. The effect of various parameters such as pH, temperature, irradiation time, amounts of nanophotocatalyst and nanocomposite, and ultrasonic intensity on degradation rates was investigated. Then based on the Langmuir–Hinshelwood approach, reaction rates and adsorption equilibrium constants were calculated. The nanophotocatalyst and nanocomposite were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and UV‐Vis spectroscopic methods. It was observed that InVO₄–TiO₂ nanopowder was more reactive than pure InVO₄ in the degradation of azo dyes under both conditions of visible light and ultrasonic irradiations. It was noticeable that degradation percent was more under ultrasonic irradiation rather than under visible light irradiation.     

Theoretical prediction of the host–guest interactions between novel photoresponsive nanorings and C60: A strategy for facile encapsulation and release of fullerene

A series of photoresponsive‐group‐containing nanorings hosts with 12～14 Å in diameter is designed by introducing different number of azo groups as the structural composition units. And the host–guest interactions between fullerene C₆₀ and those nanoring hosts were investigated theoretically at M06‐2X/6‐31G(d)//M06‐L/MIDI! and wB97X‐D/6‐31G(d) levels. Analysis on geometrical characteristics and host–guest binding energies revealed that the designed nanoring molecule (labeled as 7 ) which is composed by seven azo groups and seven phenyls is the most feasible host for encapsulation of C₆₀ guest among all candidates. Moreover, inferring from the simulated UV‐vis‐NIR spectroscopy, the C₆₀ guest could be facilely released from the cavity of the host 7 via configuration transformation between trans‐form and cis‐form of the host under the 563 nm photoirradiation. Additionally, the frontier orbital features, weak interaction regions, infrared, and NMR spectra of the C₆₀@7 host–guest complex have also been investigated theoretically. © 2015 Wiley Periodicals, Inc.     

Conversion of 1,3‐Dimethyl‐5‐(Arylazo)‐6‐Amino‐Uracils to 1,3‐Dimethyl‐5‐(Arylazo)‐Barbituric Acids: Spectroscopic Characterization,Photophysical Property and Determination of pKa of the Products

The study of inter‐conversion between molecules, especially biologically and pharmaceutically important molecules, is extremely important. This study reports the inter‐conversion between two azo‐derivtives: azo‐6‐aminouracils to azo‐barbituric acids. We successfully converted the 1,3‐dimethyl‐5‐(arylazo)‐6‐aminouracils ( Uazo‐1 to Uazo‐4 ) to 1,3‐dimethyl‐5‐(arylazo)‐barbituric acids ( BAazo‐1 to BAazo‐4 ) (where aryl?C₆H₅‐( 1 ); p‐MeC₆H₄‐( 2 ), p‐ClC₆H₄‐( 3 ), and p‐NO₂C₆H₄‐( 4 )) following an acid‐hydrolysis path. The products were characterized using spectroscopic tools like UV‐vis, IR, and NMR spectroscopy. UV‐vis spectra of the as‐prepared dyes reveal that in contrast to the azo‐6‐aminouracils they are hardly responsive towards solvatochromism. IR spectra exhibit three characteristic >C?O frequencies for as‐prepared azobarbituric acids instead of two for mother azo‐6‐aminouracils. ¹H NMR spectra which reflect the existence of solution species evidence the absence of >C?NH group (characteristic imido‐H at the 6‐position of hydrazone species of azo‐6‐aminouracils) and consequence presence of >C?O group at the same position in as‐prepared azobarbituric acids. They exhibit structural emissions in the range of 400–440 nm upon excitation at 360 nm. The determined acid dissociation constant (pKa) values of BAazos increase according to the following sequence: BAazo ‐ 2 > 1 > 3 > 4 .     

Ring transformations of heterocyclic compounds. XXIII. The UV irradiation product of photochromic 2,4,6‐triaryl‐1‐(spiro[2H‐l‐benzopyran‐2,2′‐indoline]‐6‐yl)pyridinium salts ‐ A phenolate betaine or a pyridinium substituted merocyanine dye?

The synthesis of the novel 2,4,6‐triaryl‐1‐(spiro[2H‐1‐benzopyran‐2,2′‐indoline]‐6‐yl)pyridiniumper‐chlorates 4 by reaction of 5 ‐nitrosalicylaldehydes 6 with 1,3,3‐trimethyl‐2‐methyleneindoline ( 7 ) to 6‐nitro‐spiro[2H‐1‐benzopyran‐2,2′‐indolines] 1 , their stannous chloride reduction to the 6‐amino derivatives 8 , followed by a 2,6‐[C₅+N] ring transformation with 2,4,6‐triarylpyrylium perchlorates 9 , is reported. UV irradiation experiments in twenty solvents of different polarity prove their photochromic properties and show that the photochemically generated negative solvatochromic dyes 5 , formed by ring opening of the benzopyran moiety of 4 , are rather merocyanine than pyridinium phenolate betaine dyes.     

Application of palladium nanoparticle‐decorated Artemisia abrotanum extract‐modified graphene oxide for highly active catalytic reduction of methylene blue,methyl orange and rhodamine B

A green palladium‐based catalyst supported on Artemisia abrotanum extract‐modified graphene oxide (Pd NPs/RGO‐A. abrotanum) hybrid material has been used as a recoverable and heterogeneous nanocatalyst for the catalytic reduction of various dyes, including methylene blue, methyl orange and rhodamine B, in the presence of NaBH₄ as reducing agent in aqueous medium at room temperature. With the help of UV–visible spectroscopy, the catalytic reactions were investigated. According to the results, these reactions followed the pseudo‐first‐order rate equation.     

A Novel Kinetic Approach for Photocatalytic Degradation of Azo Dye with CdS and Ag/CdS Nanoparticles Fixed on a Cement Bed in a Continuous‐Flow Photoreactor

Azo dyes are one of the synthetic dyes that have been used in many textile industries. Azo dye and their intermediate products are toxic, carcinogenic, and mutagenic to aquatic life. Removal of azo dyes is one of the main challenges before releasing the wastes discharged by textile industries. Photocatalytic degradation of azo dyes by nanoparticles is one of the environment‐friendly methods used for the removal of dyes from textile effluents. Therefore, this study focused on degradation of azo dye, Direct Red 264. Photocatalytic degradation of DR 264 azo dye was investigated using CdS and Ag/CdS nanoparticles immobilized on a cement bed in a continuous‐flow photoreactor under UV‐C exposure. The effect of the parameters of type and mass of catalyst, temperature, flow rate, dye concentration, and light intensity were evaluated for azo dye removal. Under optimal conditions, photocatalytic degradation of DR 264 azo dye using Ag/CdS nanoparticles immobilized on a cement bed in a continuous‐flow photoreactor obtained an efficiency of 99.99%. A developed kinetic model was proposed based on the intrinsic elementary reactions. The proposed model is in a good agreement with the Langmuir–Hinshelwood (L–H) equation. The pseudo–steady‐state approximation has considered for the concentration of hydroxyl radicals associated with the L–H model under certain conditions and explains consistently the dependence of the apparent kinetic parameter, k_obs (the reaction rate constant), and K_R (the adsorption equilibrium constant) with the light intensity. Based on the model, k_obs for Ag/CdS was greater than the CdS nanoparticles.     

Tunable Electronic Properties of a Proton‐Responsive N,N‐Dimethylaminoazobenzene Fullerene (C60) Dyad

A basic N,N‐dimethylaminoazobenzene–fullerene (C₆₀) dyad molecular skeleton is modelled and synthesized. In spite of the myriad use of azobenzene as a photo‐ and electrochromic moiety, the idea presented herein is to adopt a conceptually different path by using it as a bridge in a donor–bridge–acceptor single‐molecular skeleton, connecting the electron acceptor N‐methylfulleropyrrolidine with an electron donor N,N‐dimethylaniline. Addition of trifluoroacetic acid (TFA) results in a drastic colour change of the dyad from yellow to pink in dichloromethane (DCM). The structure of the protonated species are established from electronic spectroscopy and time‐dependent density functional theory (TD‐DFT) calculations. UV/Vis spectroscopic investigations reveal the disappearance of the 409 nm ¹(π→π*) transition with appearance of new features at 520 and 540 nm, attributed to protonated β and α nitrogens, respectively, along with a finite weight of the C₆₀ pyrrolidinic nitrogen. Calculations reveal intermixing of n_(N?N)→π*_(N?N) and charge transfer (CT) transitions in the neutral dyad, whereas, the n_(N?N)→π*_(N?N) transition in the protonated dyad is buried under the dominant ¹(π →π*) feature and is red‐shifted upon Gaussian deconvolution. The experimental binding constants involved in the protonation of N,N‐dimethylanilineazobenzene and the dyad imply an almost equal probability of existence of both α‐ and β‐protonated forms. Larger binding constants for the protonated dyads imply more stable dyad complexes than for the donor counterparts. One of the most significant findings upon protonation resulted in frontier molecular orbital (FMO) switching with the dyad LUMO located on the donor part, evidenced from electrochemical investigations. The appearance of a new peak, prior to the first reduction potential of N‐methylfulleropyrrolidine, clearly indicates location of the first incoming electron on the donor‐centred LUMO of the dyad, corroborated by unrestricted DFT calculations performed on the monoanions of the protonated dyad. The protonation of the basic azo nitrogens thus enables a rational control over the energetics and location of the FMOs, indispensable for electron transport across molecular junctions in realizing futuristic current switching devices.     

Simultaneous formation of platinum‐based nanocatalysts and degradation of dyes at oil/water interface: Comparative morphological and kinetic studies

To decrease the water pollution of textile industries with a large amount of toxic and non‐biodegradable colored dye effluents, an efficient technique is required to safely remove harmful pollutants. In this paper, the reaction between azo dyes and NaBH₄ catalyzed by nanoparticles (NPs) thin films has been studied. We report insitu degradation of methyl orange (MO) and methyl red (MR) by using Pt‐based thin films monitored by UV–Vis spectroscopy. We have synthesized different thin films such as Pt, PtPd, PtFeFe₂O₃, PtNi and PtAu films from Pt organometallic precursor in the MO and MR medium (dye degradation and NPs formation is happened simultaneously) and activity of these films were compared in the complete degradation of MO and MR dyes. Rate constants for the catalyzed reactions have been determined. PtPd NPs thin film has shown the highest rate constant for the degradation of MO and MR within only a few seconds due to its well‐ordered structure. Furthermore, the effect of presence of MO on the morphology of NPs was investigated.     

Thermal and mass spectral characterization of novel azo dyes of p-acetoamidophenol in comparison with Hammett substituent effects and molecular orbital calculations

Four novel azo compounds were synthesized: o-phenylazo-(C₁₄H₁₃N₃O₂) (I), p-bromo-o-phenylazo-(C₁₄H₁₃BrN₃O₂) (II), p-methoxy-o-phenylazo-(C₁₅H₁₆N₃O₃) (III), and p-nitro-o-phenylazo-p-acetamidophenol (C₁₄H₁₃N₄O₄) (IV). These compounds were carefully investigated using elemental analyses, IR, and thermal analyses (TA) in comparison with electron ionization (EI) mass spectral (MS) fragmentation at 70 eV. Semi-empirical MO calculation, PM3 procedure, has been carried out on the four azo dyes (I–IV), both as neutral molecules and the corresponding positively charged molecular ions. These included molecular geometries (bond length, bond order, and charge distribution, heats of formation, and ionization energies). The mass spectral fragmentation pathways and thermal decomposition mechanisms were reported and interpreted on the basis of molecular orbital (MO) calculations. They are found to be highly correlated to each other. Also, the Hammett’s effects of p-methoxy, p-bromo, and p-nitro-substituents of phenyl azo groups on the thermal stability of these dyes (I–IV) are studied by experimental (TA and MS) in comparison with MO calculations, and the data obtained are discussed. This research aimed chiefly to throw more light on the structures of the four prepared azo derivatives of acetoamidophenol (p-cetamol). The data refering to the thermal stability of these dyes can be used in industry for effective dyeing purposes under different thermal conditions.     

Enhanced photocatalytic activity of Ag3PO4 via Fullerene C60 modification

Fullerene‐C₆₀‐modified Ag₃PO₄ photocatalysts (C₆₀/Ag₃PO₄) were prepared via facile chemical precipitation. The structures, morphology and photocatalytic properties of C₆₀/Ag₃PO₄ were characterized by X‐ray diffractometry (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectrometry, and ultraviolet–visible (UV–vis) absorption spectrometry. C₆₀/Ag₃PO₄ exhibits considerably higher photocatalytic activity for degradation of Methyl Orange. The degradation conversion reached 93% after 8 min of light irradiation. Besides, the enhancement of photocatalytic activity could be attributed to the active species ?OH_, which can be ascribed to strong synergistic effect between Fullerene C₆₀ and Ag₃PO₄.     

Facile Soap‐Free Miniemulsion Polymerization of Methyl Methacrylate via Reverse Atom Transfer Radical Polymerization

A facile soap‐free miniemulsion polymerization of methyl methacrylate (MMA) was successfully carried out via a reverse ATRP technique, using a water‐soluble potassium persulfate (KPS) or 2,2′‐azobis(2‐methylpropionamidine) dihydrochloride (V‐50) both as the initiator and the stabilizer, and using an oil‐soluble N,N‐n‐butyldithiocarbamate copper (Cu(S₂CN(C₄H₉)₂)₂) as the catalyst without adding any additional ligand. Polymerization results demonstrated the “living”/controlled characteristics of ATRP and the resultant latexes showed good colloidal stability with average particle size around 300–700 nm in diameter. The monomer droplet nucleation mechanism was proposed. NMR spectroscopy and chain‐extension experiments under UV light irradiation confirmed the attachment and livingness of UV light sensitive  S C(S) N(C₄H₉)₂ group in the chain end.     

A Ruthenium Complex–Porphyrin–Fullerene‐Linked Molecular Pentad as an Integrative Photosynthetic Model

A ruthenium complex, porphyrin sensitizer, fullerene acceptor molecular pentad has been synthesized and a long‐lived hole–electron pair was achieved in aqueous solution by photoinduced multistep electron transfer: Upon irradiation by visible light, the excited‐state of a zinc porphyrin (¹ZnP*) was quenched by fullerene (C₆₀) to afford a radical ion pair, ^1,3(ZnP^.+‐C₆₀^.−). This was followed by the subsequent electron transfer from a water oxidation catalyst unit (Ru^II) to ZnP^.+ to give the long‐lived charge‐separated state, Ru^III‐ZnP‐C₆₀^.−, with a lifetime of 14 μs. The ZnP worked as a visible‐light‐harvesting antenna, while the C₆₀ acted as an excellent electron acceptor. As a consequence, visible‐light‐driven water oxidation by this integrated photosynthetic model compound was achieved in the presence of sacrificial oxidant and redox mediator.     

含三苯胺类富勒烯吡咯烷衍生物的合成、表征及理论计算

N-Methyl-2-（4-N,N-diphenylaminophenyl）fulleropyrrolidine and N-methyl-2-（4-di-p-tolylaminophenyl）fulleropyrrolidine were synthesized via the 1,3-dipolar cycloaddition reactions under microwave irradiation. The molecular structures were identified and characterized by MS, UV-Vis, FT-IR, ^1H NMR and fluorescence spectra. Photoinduced intramolecular electron transfer process from C60 moiety to triphenylamine moiety have been studied by nanosecond laser flash photolysis. The optimized structure and the distribution of the frontier molecular orbitals for C60-TPA were obtained by using DFT method at B3LYP/6-31G（d） level. The results indicated that the intramolecular photoinduced electron transfer could occur in these compounds, which were in excellent agreement with the nanosecond transient absorption spectra observed experimentally in polar solvent. The electronic spectrum of the compound C60-TPA was studied by ZINDO method on the basis of the optimized geometrics, which was essentially consistent with experimental values.     

Azo dyes degradation using TiO2-Pt/graphene oxide and TiO2-Pt/reduced graphene oxide photocatalysts under UV and natural sunlight irradiation

The photocatalytic degradation of azo dyes with different structures (amaranth, sunset yellow and tartrazine) using TiO₂-Pt nanoparticles (TPt), TiO₂-Pt/graphene oxide (TPt-GO) and TiO₂-Pt/reduced graphene oxide (TPt-rGO) composites were investigated in the presence of UV and natural sunlight irradiation. The composites were prepared by a combined chemical-thermal method and characterized by Transmission Electron Microscopy (TEM), X-ray powder diffraction (XRD), Infrared (FTIR) and UV–Vis spectroscopy. The modification of TiO₂-Pt with graphene oxide shifted its optical absorption edge towards the visible region and increased its photocatalytic activity under UV and natural sunlight irradiation. The efficiency of catalysts on azo dyes degradation (in similar conditions) reached high values (above 99%) under sunlight conditions, proving the remarkable photocatalytic activities of obtained composites. TPt-GO nanocomposite exhibited higher photoactivity than TPt or TPt-rGO, demonstrating degradation efficiencies of 99.56% for amaranth, 99.15% for sunset yellow and 96.23% for tartrazine. The dye photodegradation process follows a pseudo-first-order kinetic with respect to the Langmuir-Hinshelwood reaction mechanism. A direct dependence between azo dyes degradation rate and chemical structure of dyes has been observed.     

Water‐Soluble Gold Nanoparticles: From Catalytic Selective Nitroarene Reduction in Water to Refractive Index Sensing

Water‐soluble gold nanoparticles (Au NPs) stabilized by a nitrogen‐rich poly(ethylene glycol) (PEG)‐tagged substrate have been prepared by reduction of HAuCl₄ with NaBH₄ in water at room temperature. The morphology and size of the nanoparticles can be controlled by simply varying the gold/stabilizer ratio. The nanoparticles have been fully characterized by TEM, high‐resolution (HR) TEM, electron diffraction (ED), energy‐dispersive X‐ray spectroscopy (EDS), UV/Vis, powder XRD, and elemental analysis. The material is efficient as a recyclable catalyst for the selective reduction of nitroarenes with NaBH₄ to yield the corresponding anilines in water at room temperature. Furthermore, the potential ability of the Au NPs as a refractive index sensor owing to their localized surface plasmon resonance (LSPR) effect has also been assessed.     

Sensing and photocatalytic properties of nanosized Cu(I)CN organotin supramolecular coordination polymer based on pyrazine

Orange prismatic crystals of the supramolecular coordination polymer (SCP) _∞³[Cu(CN)₂(Me₃Sn)(Pyz)], SCP 1 , were synthesized using a self‐assembly method under ambient conditions. Nanosized 1 was obtained using the same molar ratio in water by ultrasonic irradiation. SCP 1 was characterized using single‐crystal X‐ray diffraction, elemental analysis, thermal analysis and Fourier transform infrared spectroscopy. SCP 1 and its nanosized 1 particles were also examined using powder X‐ay diffraction and scanning electron microscopy. The luminescence emission of SCP 1 was studied as well as its use as a sensor for the detection of common organic solvents and metal ions. Also, the catalytic activities of nanosized 1 towards various organic dyes were investigated under ambient conditions, UV irradiation and ultrasonic irradiation. Nanosized 1 as a heterogeneous nanoparticle catalyst exhibits high catalytic activity for the degradation of eosin‐Y and acid blue dyes. The mechanism of degradation investigated using various scavenger techniques is proposed and discussed. The catalytic oxidation process is mainly caused by ?OH radicals.     

Two azo pigments based on β‐naphthol

There has been much discussion in the literature of the azo–hydrazone tautomerism of pigments. All commercial azo pigments with β‐naphthol as the coupling compound adopt the hydrazone tautomeric form (Ph—NH—N=C) in the solid state. In contrast, the red pigments 1‐[4‐(dimethylamino)phenyldiazenyl]‐2‐naphthol, C₁₈H₁₇N₃O, (1a), and 1‐[4‐(diethylamino)phenyldiazenyl]‐2‐naphthol, C₂₀H₂₁N₃O, (1b), have been reported to be azo tautomers or a mixture of azo and hydrazone tautomers in the solid state. To prove these observations, both compounds were synthesized, recrystallized and their crystal structures redetermined by single‐crystal structure analysis. Difference electron‐density maps show that the H atoms of the hydroxyl groups are indeed bonded to the O atoms. Nevertheless, a small amount of the hydrazone form seems to be present. Hence, the compounds are close to being `real' azo compounds. Compound (1a) crystallizes with a herring‐bone structure and compound (1b) forms a rare double herring‐bone structure.     

Structure‐Dependent Photoinduced Electron Transfer in Fullerodendrimers with Light‐Harvesting Oligophenylenevinylene Terminals

Oligophenylenevinylene (OPV)‐terminated phenylenevinylene dendrons G1 – G4 with one, two, four, and eight “side‐arms”, respectively, were prepared and attached to C₆₀ by a 1,3‐dipolar cycloaddition of azomethine ylides generated in situ from dendritic aldehydes and N‐methylglycine. The relative electronic absorption of the OPV moiety increases progressively along the fullerodendrimer family C₆₀G1 – C₆₀G4 , reaching a 99:1 ratio for C₆₀G4 (antenna effect). UV/Vis and near‐IR luminescence and transient absorption spectroscopy was used to elucidate photoinduced energy and electron transfer in C₆₀G1 – C₆₀G4 as a function of OPV moiety size and solvent polarity (toluene, dichloromethane, benzonitrile), taking into account the fact that the free‐energy change for electron transfer is the same along the series owing to the invariability of the donor–acceptor couple. Regardless of solvent, all the fullerodendrimers exhibit ultrafast OPV→C₆₀ singlet energy transfer. In CH₂Cl₂, the OPV→C₆₀ electron transfer from the lowest fullerene singlet level (¹C₆₀*) is slightly exergonic (ΔG_CS≈0.07 eV), but is observed, to an increasing extent, only in the largest systems C₆₀G2 – C₆₀G4 with lower activation barriers for electron transfer. This effect has been related to a decrease of the reorganization energy upon enlargement of the molecular architecture. Structural factors are also at the origin of an unprecedented OPV→C₆₀ electron transfer observed for C₆₀G3 and C₆₀G4 in apolar toluene, whereas in benzonitrile, electron transfer occurs in all cases. Monitoring of the lowest fullerene triplet state by sensitized singlet oxygen luminescence and transient absorption spectroscopy shows that this level is populated through intersystem crossing and is not involved in photoinduced electron transfer.     

Manganese(III) porphyrin anchored onto multiwall carbon nanotubes: An efficient and reusable catalyst for the heterogeneous reduction of aldehydes and ketones

Reduction of a variety of carbonyl compounds with NaBH₄, using Mn-porphyrin, meso-tetrakis(4-hydroxyphenyl)porphyrinatomanganese(III), supported onto functionalized multiwall carbon nanotubes has been investigated. The heterogeneous catalyst was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–vis spectroscopy. The amount of catalyst loading on the nanotubes was determined by atomic absorption spectroscopy. Thermogravimetric analysis (TGA) demonstrated that the nanocatalyst was thermally stable to almost 300 °C, exhibiting high thermostability of the catalyst over a broad range of temperatures. This heterogeneous catalyst proved to be an efficient catalyst in the aerobic reduction of various aldehydes and ketones with NaBH₄. In the presence of the nanocatalyst, NaBH₄ can readily reduce a variety of aldehydes in good to excellent yields (50–100%) and ketones in excellent yields (100%) to their corresponding alcohols. The separation of the catalyst is very simple and economic. Also, FTIR spectra after four successive cycles showed that the catalyst was strongly anchored to the nanotubes.     

Intramolecular electronic communication in a dimethylaminoazobenzene–fullerene C60 dyad: An experimental and TD‐DFT study

An electronically push–pull type dimethylaminoazobenzene–fullerene C₆₀ hybrid was designed and synthesized by tailoring N,N‐dimethylaniline as an electron donating auxochrome that intensified charge density on the β‐azonitrogen, and on N‐methylfulleropyrrolidine (NMFP) as an electron acceptor at the 4 and 4′ positions of the azobenzene moiety, respectively. The absorption and charge transfer behavior of the hybrid donor‐bridge‐acceptor dyad were studied experimentally and by performing TD‐DFT calculations. The TD‐DFT predicted charge transfer interactions of the dyad ranging from 747 to 601 nm were experimentally observed in the UV‐vis spectra at 721 nm in toluene and dichloromethane. A 149 mV anodic shift in the first reduction potential of the N?N group of the dyad in comparison with the model aminoazobenzene derivative further supported the phenomenon. Analysis of the charge transfer band through the orbital picture revealed charge displacement from the n_(N?N) (nonbonding) and π _(N?N) type orbitals centered on the donor part to the purely fullerene centered LUMOs and LUMO+n orbitals, delocalized over the entire molecule. The imposed electronic perturbations on the aminoazobenzene moiety upon coupling it with C₆₀ were analyzed by comparing the TD‐DFT predicted and experimentally observed electronic transition energies of the dyad with the model compounds, NMFP and (E)‐N,N‐dimethyl‐4‐(p‐tolyldiazenyl)aniline (AZNME). The n_(N?N) → π*_(N?N) and π_(N?N) → π*_(N?N) transitions of the dyad were bathochromically shifted with a significant charge transfer character. The shifting of π_(N?N) → π*_(N?N) excitation energy closer to the n → π*_(N?N) in comparison with the model aminoazobenzene emphasized the predominant existence of charge separated quinonoid‐like ground state electronic structure. Increasing solvent polarity introduced hyperchromic effect in the π_(N?N) → π*_(N?N) electronic transition at the expense of transitions involved with benzenic states, and the extent of intensity borrowing was quantified adopting the Gaussian deconvolution method. On a comparative scale, the predicted excitation energies were in reasonable agreement with the observed values, demonstrating the efficiency of TD‐DFT in predicting the localized and the charge transfer nature of transitions involved with large electronically asymmetric molecules with HOMO and LUMO centered on different parts of the molecular framework. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010