Long-wavelength Absorption Maximum Research Articles

Styryl hemicyanine-DNA assembly for selective Hg2+ sensing and molecular computing

A styryl dye with a chromophore based on methyl-benzothiazolium and 1-methyl-4-phenylpiperazine end group was synthesized under new improved reaction conditions. The synthesis was carried out in a way that ensured the direct production of a pure (>98 %) dye. The dye exhibits pronounced vertical and horizontal solvatochromism in both light absorption and fluorescence spectra. In the UV–Vis spectra of the dye, a difference in the longest wavelength absorption maximum from dichloromethane to water of about 100 nm was observed. In buffer (pH = 7.2), the dye absorbs at 445 nm, and in dichloromethane at 547 nm. The interaction of the dye with DNA and with protons and various metal ions was investigated, and the ability of the target fluorochrome to be used as a logic gate in the simultaneous presence of H+ and DNA was demonstrated. The dye is sensitive in the presence of mercury ions as well.

Extension of nature's NIR-I chromophore into the NIR-II region.

The development of chromophores that absorb in the near-infrared (NIR) region beyond 1000 nm underpins numerous applications in medical and energy sciences, yet also presents substantial challenges to molecular design and chemical synthesis. Here, the core bacteriochlorin chromophore of nature's NIR absorbers, bacteriochlorophylls, has been adapted and tailored by annulation in an effort to achieve absorption in the NIR-II region. The resulting bacteriochlorin, Phen2,1-BC, contains two annulated naphthalene groups spanning meso,β-positions of the bacteriochlorin and the 1,2-positions of the naphthalene. Phen2,1-BC was prepared via a new synthetic route. Phen2,1-BC is an isomer of previously examined Phen-BC, which differs only in attachment via the 1,8-positions of the naphthalene. Despite identical π-systems, the two bacteriochlorins have distinct spectroscopic and photophysical features. Phen-BC has long-wavelength absorption maximum (912 nm), oscillator strength (1.0), and S1 excited-state lifetime (150 ps) much different than Phen2,1-BC (1292 nm, 0.23, and 0.4 ps, respectively). These two molecules and an analogue with intermediate characteristics bearing annulated phenyl rings have unexpected properties relative to those of non-annulated counterparts. Understanding the distinctions requires extending concepts beyond the four-orbital-model description of tetrapyrrole spectroscopic features. In particular, a reduction in symmetry resulting from annulation results in electronic mixing of x- and y-polarized transitions/states, as well as vibronic coupling that together reduce oscillator strength of the long-wavelength absorption manifold and shorten the S1 excited-state lifetime. Collectively, the results suggest a heuristic for the molecular design of tetrapyrrole chromophores for deep penetration into the relatively unutilized NIR-II region.

SYNTHESIS AND MOLECULAR STRUCTURE OF TETRA-3-(4-CYCLOHEXYLPHENOXY)PHTHALOCYANINE ALUMINUM CHLORIDE COMPLEX

This work is devoted to the synthesis and study of the molecular structure of the tetra-3-(4-cyclohexylphenoxy)phthalocyanine aluminum chloride complex. The synthesis of tetra-3-(4-cyclohexylphenoxy)phthalocyanine aluminum chloride was carried out by the "nitrile" method. The complex was purified by M60 silica gel column chromatography, eluting with the chromophore. IR-spectroscopy and mass-spectrometry (MALDI-TOF) were used for the identification of the obtained compound. The electronic absorption spectrum was obtained in tetrahydrofurane and interpreted by quantum-chemical calculations in TDDFT approximation. The conformational search was performed utilizing the CREST program and GFN2-xTB approximation, followed by DFT calculations of the “single-point” energies of the found conformations. For each configuration, "single-point" energy calculations were carried out in the B3LYP-D3/dgdzvp approximation and the most energetically favorable structure was identified. It has been established that the most energetically favorable structure of the tetra-3-(4-cyclohexylphenoxy)phthalocyanine aluminum chloride molecule is characterized by a helical mutual arrangement of bulky substituents on the same side of the macrocyclic plane. The interpretation of the electronic absorption spectrum was made on the basis of TDDFT calculations in the B3LYP-D3/def2-TZVP and CAM-B3LYP/def2-TZVP approximations with and without solvent (tetrahydrofuran, THF) within the C-PCM continuum solvation model. For both approximations, taking into account the solvent leads to a shift of the long-wavelength absorption maximum by 25–33 nm towards the experimental value (704 nm). The best agreement with experiment is achieved with the [PCM] CAM-B3LYP/def2-TZVP method.The simulated electronic spectrum is compared with the previously obtained spectra for complexes of Al(Cl) with tetrabenzoporphyrin (ClAlTBP) and tetrapyrazinoporphyrazine (ClAlTPyzPA).

Polymer composition with phenanthrenequinone for recording relief holographic gratings

The formation of periodic reliefs of the thickness of photosensitive polymer layers after recording holographic gratings in them and stimulating material deformations by reversible plasticization in a non-solvent liquid is considered. The phenomenon was studied for the composition of a copolymer with side anthracene groups — phenanthrenquinone. Phenantrenquinone transfers the energy of electronic excitation to oxygen molecules entering through the open surface of the polymer layer which then cause the oxidation of anthracene fragments. Holographic gratings with a period of 2–5 μm were recorded by laser radiation at a wavelength of 532 nm in layers about 1 μm thick. The photoreliefs were formed during the subsequent swelling of the layer in the medium of a hydrocarbon developer. The photosensitized oxidation of the anthracene groups of the new polymer under the action of optical radiation in the spectral range 408–532 nm was studied using the electron absorption spectra. It is shown that approaching the excitation wavelength to the long-wavelength absorption maximum of phenanthrenquinone (410 nm) makes it possible to increase the sensitivity of the material layer by a factor of 15 compared to layers with methylene blue as a photosensitizer. It has been experimentally established that the amplitude of weak periodic reliefs of a deformation nature (height less than 0.01 μm), which appear immediately after the recording of holographic gratings, increases many times during the treatment of the layer with liquid hydrocarbon. Their maximum value reaches 25 % of the thickness of the recording layer. Presumably, the deformation of the inhomogeneously irradiated layer is stimulated by the transfer of the polymer material into a highly elastic state during its swelling. Photoreliefs are stable after drying. Their strength can be increased by photocrosslinking the material as a result of photodimerization of residual anthracene groups under uniform irradiation with light at a wavelength of 365 nm. The non-sinusoidality of the photorelief reduces the diffraction efficiency achievable with total reflection to values less than 0.20. The studied polymer composition can be used to form relief-phase diffractive optical elements by radiation in the blue-green region of the spectrum, provided by a number of high-power laser sources.

Synthesis, Structure and Photochemistry of Dibenzylidenecyclobutanones.

A series of symmetrical dibenzylidene derivatives of cyclobutanone were synthesized with the goal of studying the physicochemical properties of cross-conjugated dienones (ketocyanine dyes). The structures of the products were established and studied by X-ray diffraction and by NMR and electronic spectroscopy. All the products had E,E-geometry. The oxidation and reduction potentials of the dienones were determined by cyclic voltammetry. The potentials were shown to depend on the nature, position, and number of substituents in the benzene rings. A linear correlation was found between the difference of the electrochemical oxidation and reduction potentials and the energy of the long-wavelength absorption maximum. This correlation can be employed to analyze the properties of other compounds of this type. Quantum chemistry was used to explain the observed regularities in the electrochemistry, absorption, and fluorescence of the dyes. The results are in good agreement with the experimental redox potentials and spectroscopy data.

Structure-Property Relationships of Dibenzylidenecyclohexanones.

A series of symmetrical dibenzylidene derivatives of cyclohexanone were synthesized with the goal of studying the physicochemical properties of cross-conjugated dienones (ketocyanine dyes). The structures of the products were established and studied by X-ray diffraction, NMR spectroscopy, and electronic spectroscopy. All products had the E,E-geometry. The oxidation and reduction potentials of the dienones were determined by cyclic voltammetry. The potentials were shown to depend on the nature, position, and number of substituents in the benzene rings. A linear correlation was found between the difference of the electrochemical oxidation and reduction potentials and the energy of the long-wavelength absorption maximum. This correlation can be employed to analyze the properties of other compounds of this type. The frontier orbital energies and the vertical absorption and emission transitions were calculated using quantum chemistry. The results are in good agreement with experimental redox potentials and spectroscopic data.

Photophysical and molecular docking approach on the interaction of water-soluble simple keto sugar with acridinedione dyes

Photophysical studies in association with molecular docking (MD) methods were employed in the determination of various molecular interactions existing between d-Fructose in the presence of a photoinduced electron transfer (PET) and non-PET based acridinedione (AD) dyes in water. Addition of fructose to AD dyes resulted in a decrease in the absorbance at the longest wavelength absorption maxima accompanied with the formation of an isosbestic point signifying a ground state complex formation. The ground state interaction between fructose and dye is presumably attributed to hydrogen-bonding (HB) and was authenticated by MD studies. Interestingly, the excited state characteristics of PET dye (ADR1) is found to be entirely different from that of non-PET dye (ADR2) on the introduction of fructose. A fluorescence quenching phenomenon is observed in PET dye, whereas an enhancement results in that of a non-PET dye. Fructose promotes electron transfer (ET) through space resulting in a decrease in the fluorescence intensity of ADR1 dye. On the contrary, it suppresses the PET process in ADR2 dye resulting in an increase in the quantum yield. Fluorescence lifetime studies of fructose with AD dyes results in a multi exponential lifetime with varying proportions. The presence of biexponential lifetime components justifies the existence of more than one distinguishable micro heterogenous environment in the aqueous phase containing unequal proportion of distribution of fructose and water molecules around the close vicinity of AD dyes. The local excited (LE) state of the fluorophore experiences a large variation in the excited state such that the emission intensity and fluorescence lifetime are governed by solute induced and solvent mediated HB interactions. MD studies further establish the existence of HB interaction of dye-fructose, wherein the dye acts as the HB donor and sugar as the acceptor. Docking techniques establishes clear and authentic information on the HB donor and acceptor sites in dye and sugar molecule resulting in a most stable conformer. The nature of interaction of a simple sugar molecule with water soluble fluorophores are explored in depth by fluorescence techniques in coordination with MD methods is imparted in the present study.

Circular dichroism and resonance Raman spectroscopies of bacteriochlorophyll b-containing LH1-RC complexes.

The core light-harvesting complexes (LH1) in bacteriochlorophyll (BChl) b-containing purple phototrophic bacteria are characterized by a near-infrared absorption maximum around 1010nm. The determinative cause for this ultra-redshift remains unclear. Here, we present results of circular dichroism (CD) and resonance Raman measurements on the purified LH1 complexes in a reaction center-associated form from a mesophilic and a thermophilic Blastochloris species. Both the LH1 complexes displayed purely positive CD signals for their Qy transitions, in contrast to those of BChl a-containing LH1 complexes. This may reflect differences in the conjugation system of the bacteriochlorin between BChl b and BChl a and/or the differences in the pigment organization between the BChl b- and BChl a-containing LH1 complexes. Resonance Raman spectroscopy revealed remarkably large redshifts of the Raman bands for the BChl b C3-acetyl group, indicating unusually strong hydrogen bonds formed with LH1 polypeptides, results that were verified by a published structure. A linear correlation was found between the redshift of the Raman band for the BChl C3-acetyl group and the change in LH1-Qy transition for all native BChl a- and BChl b-containing LH1 complexes examined. The strong hydrogen bonding and π-π interactions between BChl b and nearby aromatic residues in the LH1 polypeptides, along with the CD results, provide crucial insights into the spectral and structural origins for the ultra-redshift of the long-wavelength absorption maximum of BChl b-containing phototrophs.

Spectral Properties of an Indotricarbocyanine Dye upon Complexation by Detonation Nanodiamonds and Blood Serum Proteins

Spectral properties of an indotricarbocyanine dye upon complexation with nanodiamonds in aqueous solutions were studied. Complexation was accompanied by disappearance of the H*-aggregate absorption band at 514 nm and a bathochromic shift of long-wavelength absorption maxima from 706 to 718 nm. The dye emission spectrum was almost unchanged. The fluorescence excitation peak shifted from 706 to 710 nm. The dye carboxyl groups played an important role in the complexation of the dye to nanodiamonds based on an analysis of the IR absorption spectra. The complexes broke down and the dye molecules bonded to serum proteins in the presence of human blood serum. This was confirmed by significant increases in the fluorescence lifetime and anisotropy. The obtained complexes could be used as a basis for fluorescent biosensors.

Visible to near-IR molecular switches based on photochromic indoline spiropyrans with a conjugated cationic fragment.

Photochromic molecules which can absorb and emit light within the "biological window" (650-1450 nm) are of great interest for using in various important biomedical applications such as bio-imaging, photopharmacology, targeted drug delivery, etc. Here we present three new indoline spiropyrans containing conjugated cationic fragments and halogen substituents in the 2H-chromene moiety which were synthesized by a simple one-pot method. The molecular structure of the obtained compounds was confirmed by FT-IR, 1H and 13C NMR spectroscopy (including 2D methods), HRMS, elemental and single crystal X-ray analysis. Photochemical studies revealed the photochromic activity of spiropyrans at room temperature which caused photoswitchable fluorescence in the near-IR region after UV-irradiation. While the spirocyclic forms of compounds demonstrated absorption bands in the UV-Vis spectra with maxima in the visible region at about 445 nm and were not fluorescent, the photogenerated merocyanine isomers absorbed in the near-IR range at 708-738 nm and emitted at 768-791 nm. It was found that compound 1a with fluorine substituent possesses the most red-shifted absorption and emission bands of merocyanine form among all the known photochromic spiropyrans with maxima at 738 and 791 nm correspondingly. TD DFT calculations have shown that the longest wavelength absorption maxima of the merocyanine forms correspond to S0-S1 transitions of the isomers with at least one trans-trans-trans-configured vinylindolium fragment which brings them closer to cyanine-like structure and causes an appearance of the absorption and emission bands in the near-IR region.

Fluorescence Spectral Studies on the Interaction of Alanine and Valine with Resorcinol-Based Acridinedione Dyes in Aqueous Solution: A Comparative Study with Glycine.

Photophysical studies were carried out for simple amino acids like alanine and valine with resorcinol-based aqueous acridinedione (ADDR) dyes. ADDR dyes exhibit interesting excited-state characteristics on altering the substituents at the 9th and 10th sites (Scheme 1). The longest-wavelength absorption maxima remain the same on adding the amino acids to the fluorophore, whereas the excited-state behavior varies significantly mostly based on the nature of the substituent at the 9th position. The absence of fluorescence enhancement was observed with addition of β-alanine, l-alanine, and l-valine to ADDR1 dye (photoinduced electron transfer, PET), whereas addition of glycine exhibits enhancement accompanied with a shift toward a longer-wavelength region. Interestingly, the addition of amino acids to non-PET dyes results in a fluorescence quenching accompanied with a larger shift toward the shorter-wavelength region. The properties of fluorophore and nonfluorophore dyes in the presence of alanine or valine are found to be entirely different from those of glycine. The interaction of alanine with ADDR dyes is predominantly through H-bonding, but the structural aspects of H-bonding interactions of alanine and water are completely different from those of glycine and water. The time-correlated single-photon counting method portrays the existence of fluorophore in two distinguishable microenvironments in the presence of amino acids. The fluorescence spectral technique used as a tool in elucidating the mode of interaction of dye with neutral amino acids in aqueous solution is illustrated in the present study.

Phospholones from Diacetylenic Ketones: Synthesis, Properties, and Reactivity.

The reactivity of phosphanyl phosphonates toward diacetylenic ketones was studied. Reactions resulted in the selective formation of phospholones via phosphaalkene intermediates. Phospholones were obtained in yields of 37-96% depending on the substituent on the acetylenic unit. Reduction of the phenyl-substituted phospholone resulted in the formation of a persubstituted phosphole bearing a hydroxyl group in position 3 in 64% yield, and its oxidation led to oxaphospholone in 77% yield. Both of these modifications led to substantial changes in the optoelectronic properties of the compounds and bathochromic shifts of the longest wavelength absorption maximum.

Spiropyrans and spirooxazines 13. Synthesis and photochromic properties of benzoxazolyl-substituted spirobenzopyrans

New benzoxazolyl-substituted spiroindoline-benzopyrans with electron-withdrawing groups in the indoline fragment were obtained. These compounds exhibit positive P- and T-type photochromism. Structural correlations of the spectrokinetic properties depending on the variation of substituents in the indoline part of the spiropyran molecules were established. Electronwithdrawing groups were found to cause a bathochromic shift of the long-wavelength absorption maxima of the merocyanine isomers as compared to the unsubstituted spiropyran and decrease their lifetime. Conversely, an introduction of electron-donating groups results in a hypso chromic shift of the absorption maxima and an increase in the lifetime of the colored isomers of spiropyrans. Electron-withdrawing substituents at the position 5 of the indoline fragment cause the increase of the colorability of the spiropyrans.

New Salt Spiropyran of Indoline Series with Fluorine Substituent

Synthesis, study of structure and photochromic properties of new salt spiropyran of indoline series containing a fluorine substituent in the 6′-position of the 2H-chromene moiety have been described in the work. The structure of the compound has been confirmed by 1H NMR spectroscopy and X-ray diffraction analysis. Comparison of the structure of the compound with the previously studied analogue containing a methyl group instead of a fluorine atom in the 6′-position of the [2H]-chromene moiety has been made. This compound has been found to be photochromic, long-wavelength absorption maximum of its open form shows a bathochromic shift, and lifetime is increased three times as compared with the methyl analogue.

New series of non-toxic DNA intercalators, mitochondria targeting fluorescent dyes

Five novel benzoxazolium and benzothiazolium derived asymmetric dicationic monomethine cyanine dyes, bearing a thioester group have been synthesised via condensation of quaternary nitrogen containing heterocyclic salts in various anhydrides. Their chemical structures were evaluated by NMR, ESI/MS, IR spectroscopy, and melting point temperatures. Photophysical studies on the title compounds were performed in methanol solutions. The longest wavelength absorption maxima λmax of the studied dyes are in the region 453–508 nm. The corresponding fluorescence maxima λfl were registered within the 489–553 nm. Further spectroscopy and calorimetric techniques including circular dichroism (CD), UV–Vis, fluorescence, thermal denaturation and isothermal titration calorimetry have been applied to the studied dyes in the presence of biopolymers, in order to evaluate their staining ability as fluorescent markers. In aqueous solution the compounds exhibit no intrinsic fluorescence, however upon binding to dsDNA and dsRNA they show considerable enhancement of fluorescence intensity. Binding constants Ks of the complexes [dye–polynucleotide] have been evaluated from fluorescence spectral titrations. Although the intercalation is the predominant binding mode, the compounds show little or no effect on the cell proliferation. Upon fast cell internalization the compounds accumulate in the mitochondrial space.

Selective Conversion of P=O-Bridged Rhodamines into P=O-Rhodols: Solvatochromic Near-Infrared Fluorophores.

The substitution of an oxygen atom in rhodols with a phosphine oxide (P=O) moiety affords P=O-bridged rhodols as a new type of near-infrared (NIR) fluorophore. This compound class can be readily accessed upon exposure of the corresponding rhodamines to aqueous basic conditions. The electron-withdrawing effect of the P=O group facilitates the hydrolytic deamination, and, moreover, prolonged exposure to aqueous basic conditions generates P=O-bridged fluoresceins, that is, a series of three P=O-bridged xanthene dyes is available in one simple operation. The P=O-bridged rhodols show significant bathochromic shifts of the longest-wavelength absorption maximum (Δλ=125 nm; >3600 cm-1 ) upon changing the solvent from toluene to water, whereas the emission is shifted less drastically (Δλ=70 nm; 1600 cm-1 ). The hydrogen bonding between the P=O and C=O groups with protic solvents results in substantial stabilization of the LUMO level, which is responsible for the solvatochromism.

Synthesis and Photophysical Properties of 5-N-Arylamino-4-methylthiazoles Obtained from Direct C–H Arylations and Buchwald–Hartwig Aminations of 4-Methylthiazole

5-N-Arylamino-4-methylthiazoles were synthesized from commercially available 4-methylthiazole in three consecutive steps: (i) direct Pd-catalyzed C–H arylations of the thiazole, (ii) bromination, and (iii) Pd-catalyzed Buchwald–Hartwig aminations. The resulting thiazoles showed the longest-wavelength absorption maxima at 338–432 nm, and luminescence was observed at 455–726 nm, whereby the latter depends predominantly on the substituents at the 2-position of the thiazole core. The introduction of electron-accepting groups, in particular a nitro group, induced substantial bathochromic shifts of the fluorescence. Thiazoles containing a 3,5-bis(trifluoromethyl)phenyl group at the 2-position exhibited purple to blue emission in the solid state. The energy levels of the frontier molecular orbitals and the Kohn–Sham plots of the 5-N-arylamino-4-methylthiazoles were obtained from DFT calculations at the B3LYP/6-31+G(d,p) level of theory.

3,4-Dinitrothiophene as a central unit of quadrupolar push-pull-push systems

3,4-Dinitrothiophene has been utilized as a central acceptor unit in quadrupolar D-π-A-π-D push-pull-push chromophores. Employing cross-coupling and Knoevenagel reactions, nine novel chromophores bearing terminal methoxythiophene donor and systematically extended/varied π-linker were synthesized. Optical properties were studied by electronic absorption spectra. Fundamental optoelectronic properties were investigated by semiempirical PM7 calculations. It was shown that by varying the π-conjugated system the longest-wavelength absorption maxima can be shifted from 341 to 489 nm. The calculated HOMO–LUMO gaps were found within the range of 6.69–7.29 eV, while the second-order molecular polarizabilities can be tuned from 0.038 to 1.578 × 10 –27 esu.

Enhancing the efficiency of solution-processable bulk-heterojunction devices via a three-dimensional molecular architecture comprising triphenylamine and cyanopyridone

Through the employment of a three-dimensional molecular geometry, a novel, solution-processable small molecular organic chromophore was designed, synthesized and characterized for application in bulk-heterojunction solar cells. The new chromophore, [(5Z,5′Z,5″Z)-5,5′,5″-(((nitrilotris(benzene-4,1-diyl))tris(thiophene-5,2-diyl))tris(methanylylidene))tris(1-(2-ethylhexyl)-4-methyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile)] (coded as 3D), was based on a donor–acceptor (D–A) module where a simple triphenylamine unit served as an electron donor, cyanopyridone as an electron acceptor, and a thiophene unit as π-bridge embedded between the donor and acceptor functionalities. The optoelectronic and photovoltaic properties of 3D were directly compared with those of a structural analogue, [(Z)-5-((5-(4-(diphenylamino)phenyl)thiophen-2-yl)methylene)-1-(2-ethylhexyl)-4-methyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile)], namely 1D. The three-dimensional (otherwise termed as non-linear) design, compared to one-dimensional (or linear) design, demonstrated (1) an enhancement of light-harvesting ability by about 50%; (2) an increase in wavelength of the longest wavelength absorption maximum of thin film (633 nm vs. 581 nm) and (3) a narrower optical band-gap (1.53 eV vs. 1.65 eV). Solution-processable bulk-heterojunction devices were fabricated with 3D and 1D as donor materials. Studies on the photovoltaic and hole charge mobility properties revealed that the best 3D- [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM)-based device showed an impressive enhanced power conversion efficiency of 4.76%, an increase of greater than two-fold with respect to the efficiency of the best 1D-based device (2.11%), and a higher hole mobility of the order of 3.4 × 10−4 cm2 V−1 s−1. Not only is 3D the first reported example in the literature where cyanopyridone acceptor functionality has been used to generate a three-dimensional donor molecule but the power conversion efficiency reported here is the highest value reported so far for non-linear, star-shaped molecular architectures. These results clearly illustrated that the use of a three-dimensional geometry helped to extend molecular conjugation, thus enhancing the light-harvesting ability and short-circuit current density, while further improving the bulk-heterojunction device performance.

Synthesis, structure, electrochemistry, and photophysics of 2,5-dibenzylidenecyclopentanones containing in benzene rings substituents different in polarity

A series of cross-conjugated dienones was synthesized to study the dependence of physicochemical characteristics on the nature of substituents in the aromatic groups of symmetric cyclopentanone dibenzylidene derivatives. The structure of compounds was established by electronic, IR, and NMR spectroscopy and X-ray diffraction study. All the compounds obtained possess the E,E-geometry. In the crystalline state, the arrangement of the dienone molecules is unfavorable for the intermolecular [2+2] photocycloaddition to take place. The low-temperature phases transition for unsubstituted diphenyl derivative of cyclopentanone was detected using variable-temperature X-ray diffraction and differential scanning calorimetry. Oxidation and reduction potentials of the dienones were measured by cyclic voltammetry. Their dependence on the nature and placement of substituents in the benzene rings was demonstrated. A linear correlation (R = 0.9343) between the difference of electrochemical oxidation and reduction potentials and the energy of the long-wavelength absorption maximum was found, that allows us to recommend the use of the data obtained in the correlation analysis of other compounds of this class.