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This article shows a very satisfactory performance of the DFT Koopmans theorem analogue was demonstrated with respect to the energy intervals between the electronic levels of 4Me-BODIPY derivatives.

Monoiodo- and dibromsubstituted dipyrromethenes HL1 – HL3 were described as a highly sensitive and selective «Off-On» fluorescent chemosensor for Zn2+ based on the chelation-enhanced fluorescence (CHEF) effect. Сoordination reactions of HL1 – HL3 with Zn2+ cations are accompanied by a significant (124 to 215-fold) increase in fluorescence intensity against the background of other metal ions in the binary propanol-1/cyclohexane mixture (1:30). The fluorometric detection limit of Zn2+ ions using HL1 – HL3 sensors is from 3.0∙10−8 to 3.3·10−9 mol/L. The presence of Na+, K+, Ca2+, Mg2+, Mn2+, Ni2+, Co2+, Pb2+ cations does not interfere with the detection of Zn2+. Complexation reactions are accompanied by a visual change in the color of the solution from yellow-orange to pink-raspberry so that the HL1 – HL3 ligands can also be used as a «naked-eye» indicators of the presence of Zn2+ ions.

We have obtained a new water-soluble form of boron(III) dipyrromethene luminophores using the example of 3,3',5,5'-tetraphenyl-ms-aza-2,2'-dipyrromethenate boron(III) (BODIPY) and Cremophor® (polyethylene glycol, PEG-40). The results of a study of the spectral-luminescent properties of the studied BODIPY–Cremophor®–aqueous–alcohol medium system are presented. It is found that Cremophor® is the only one of a series of investigated excipients (PEG-400, PEG-1000, polyvinylpyrrolidone, bovine serum albumin, sodium carboxymethylcellulose) providing solubilization of BODIPY in an aqueous medium, while maintaining its intense spectral characteristics, including fluorescence and luminophore, in the red region of the spectrum. The BODIPY–Cremophor® system is tested on two mouse cell lines: metastatic breast cancer and non-metastatic skin cancer. It is shown that the introduction of the BODIPY–Cremophor® system into both cell lines of mice leads to the detachment of cell cultures from the substrate and suppression of the development of cancerous tumors. The results obtained show that immobilization of BODIPY in PEG-40 in an aqueous-alcoholic medium makes it possible to obtain preparations with prolonged action, which can be used as photosensitizers (PSs) in photodynamic therapy and for bioimaging in cell biology.

An analysis and interpretation of experimental and theoretical data on the spectral-luminescent, photophysical, and photochemical properties of dipyrromethenates are presented depending on the structure of the ligand, the complexing agent type, and the solvent and its phase state (temperature). The special features of photonics related to the violation of the physicochemical properties in the series of substituted dipyrromethenates in heteroatoms and heavy atoms (their nature, location, and the number of such substituents) are discussed.

Red-emitting distyryl substituted BODIPY dyes are among the most promising luminophors for bioimaging and optics applications. However, the practical application of BODIPYs is limited due to their high hydrophobicity and tendency to aggregate in aqueous organic solutions and solid phase. In this article, we propose an elegant solution to this problem. To this end, we carried out the detailed experimental and quantum-chemical study of the structural and spectral features of BF

This article describes the design and biological properties of a BODIPY FL-labeled monoterpenoid BF2-meso-(4-((1″R)-6″,6″-dimethylbicyclo[3.1.1]hept-2″-ene-2″)yl-methoxycarbonylpropyl)-3,3′,5,5′-te...

The spectral and luminescent properties of meso-propargylamino-boron (III) dipyrromethenate (BODIPY 1) were studied in a wide range of organic solvents of different polarities, electron- and proton-donating abilities. Effect of organic solvents on the properties of the BODIPY 1 spectral characteristics was analyzed in details. It was shown that the fluorescence of BODIPY 1 is characterized by a high sensitivity to the nature of the solvent. It was found that the complex, which emits in the blue-green region (433–486 nm), has a high quantum yield of fluorescence (~100%) in non-polar media (cyclohexane, benzene, toluene), while in proton- and especially electron donor media, sharp fluorescence quenching (2.2–31.2 times) of the dye is observed. For a better understanding of the spectral analysis results, a quantum-chemical analysis of the molecular structure, electronic structure, and spectral characteristics of BODIPY 1 was carried out. For the first time, it was shown that BODIPY 1 fluorescence quenching in proton and electron donor media is caused by the formation of a supramolecular dye complex due to specific interactions of solvent molecules with atoms of the meso-propargylamine group. Due to practically useful spectral properties, including the sensitivity of the fluorescence to the nature of the media, BODIPY 1 is recommended as a new effective fluorescent sensor of specific electron and proton donor molecules.

In this paper the synthesis and spectral properties of three new dimeric bis(BODIPY)s with two indacene domains connected by a methylene (-CH2-) spacer at 2,2-, 2,3- or 3,3- positions were reported. It was found bis(BODIPY)s exhibit a high sensitivity of fluorescence to the medium properties. To interpret solvatochromic effects of bis(BODIPY)s, a multilinear correlation analysis of bis(BODIPY)s fluorescence quantum yields with respect to solvent different parameters was carried out. To understand the features of the spectral properties of bis(BODIPY)s, we carried out a thorough quantum-chemical analysis of the structural, conformational, and spectral characteristics of bis(BODIPY)s. The obtained bis(BODIPY)s have a high potential for application as sensors of medium polarity.

Boron(III) complexes with alkyl-, phenyl-, and halogen-substituted 2,2′-dipyrromethenes (BODIPY) and meso-aza-dipyrrometenes (ms-aza-BODIPY) were synthesized. The structure relationship of the obtained coordination compounds with their luminescent characteristics is analyzed. Arylated BODIPY, in contrast to alkyl-substituted analogs, is more sensitive to interparticle interactions with a solvent, causing a decrease in the quantum yield by up to 40%. The introduction of phenyl substituents into the BODIPY molecule shifts the first absorption band bathochromic, significantly (32–37 nm) increases the Stokes shift in the emission spectrum, but reduces the probability of the S0 → S1 electronic transition as compared to alkylated complexes. Replacing the methine carbon atom with nitrogen leads to quenching of ms-aza-BODIPY fluorescence compared to BODIPY up to 5–20%. The stability of 2,2′-dipyrromethenes difluoroborates to oxidative destruction under the influence of UV irradiation in cyclohexane solutions was evaluated. It has been shown that symmetric aryl substitution in pyrrole cycles of dipyrromethene significantly increases the photostability of the corresponding compounds as compared to alkyl-substituted analogs and is an effective method of obtaining boron (III) dipyrromethenates with practically useful properties. It has been established that the replacement of the methin ms-spacer of dipyrromethene by a nitrogen atom significantly reduces the photostability of ms-aza-dipyrromethenates of boron. Halogenation of β-positions of pyrrole cycles by a factor of 5–8 reduces the photostability of difluoroborates ms-aza-dipyrromethenes in comparison with a non-halogenated analogue.

This paper is devoted to the design of a fluorescent probe based on meso-carboxysubstituted-BODIPY with a thioterpene fragment. The functional replacement of the methoxy group in the BODIPY molecule on a thioterpene fragment was carried out in order to find out the antiplatelet and anticoagulant action mechanisms of thioterpenoids and to assess the membrane and receptor factors contributions. The molecular structure of the conjugate was confirmed via UV/vis-, NMR- and MS-spectra. It is found that the probe is a high fluorescence quantum yield (to ∼100%) in the blue-green region at 509–516 nm. Molecular docking of all studied molecules showed that the BODIPY with terpenoid conjugation is an excellent way to increase their affinity to platelet receptor P2Y12.

In this article, we present synthesis, spectral characteristics, and results of DFT calculations of new CH(R)-bis(BODIPY) 1–3. They are characterized by the conformational mobility and sensitivity of fluorescence to polarity, proton-, electron donor ability and viscosity of the solvation environment. It is shown that fluorescence intensity of 1–3 increases in the homologous series of alcohols (ethanol, 1-propanol, 1-butanol, 1-octanol, 1-decanol) mainly due to decrease of medium acidic properties. The viscosity of the medium effects on the 1–3 fluorescence in a lesser degree. Compared to 1 and 2, the 3 is the most sensitive towards viscosity both in low-viscosity homologous alcohols and in high-viscosity ethanol-glycerol mixtures. In this regard, the sensitivity of fluorescence of CH(MeOPh)-bis(BODIPY) (compound 3) to the viscosity was studied in binary mixtures of polar DMF and low-polarity toluene with castor and vaseline oils, as well as to the macroviscosity of the solvate environment in mixtures of toluene with polystyrene. Prospects of the practical application of CH(R)-bis(BODIPY)s are proposed for the analysis of polarity, proton-donor properties and viscosity of the medium.

BODIPY dyes possess favorable optical properties for a variety of applications including in vivo and in vitro diagnostics. However, their utilization might be limited by their water insolubility and incompatibility with chemical modifications, resulting in low aggregation stability. Here, we outline the route for addressing this issue. We have demonstrated two approaches, based on dye entrapment in micellar coordination clusters (MCCs); this provides a general solution for water solubility as well as aggregation stability of the seven BODIPY derivatives. These derivatives have various bulky aromatic substituents in the 2,3,5,6- and meso-positions and can rotate relative to a dipyrrin core, which also provides molecular rotor properties. The molecular structural features and the presence of aromatic groups allows BODIPY dyes to be used as "supporting molecules", thus promoting micelle-micelle interaction and micellar network stabilization. In the second approach, self-micellization, following BODIPY use, leads to MCC formation without the use of any mediators, including chelators and/or metal ions. In both approaches, BODIPY exhibits an excellent optical response, at a concentration beyond its solubilization limit in aqueous media and without undesired crystallization. The suggested approaches represent systems used to encapsulate BODIPY in a capsule-based surfactant environment, enabling one to track the aggregation of BODIPY; these approaches represent an alternative system to study and apply BODIPY's molecular rotor properties. The stabilized compounds, i.e., the BODIPY-loaded MCCs, provide a unique feature of permeability to hydrophilic ligand-switching proteins such as BSA; they exhibit a bright "turn-on" fluorescence signal within the clusters via macromolecular complexation, thus expanding the possibilities of water-soluble BODIPY-loaded MCCs utilization for functional indicators.

Alkyl-halogen-dipyrromethene (Dpm) ligands coordinated with boron(III), zinc(II), and cadmium(II) were studied experimentally and theoretically to elucidate and compare influence of the coordination centers and halogen substituents (“heavy” atom effect) on observable photophysical properties. Novel and recently published experimental data were summarized and analyzed using quantum-mechanical calculations which revealed specific of the electronic structures and photo-induced dissipations in the molecular complexes. Halogenation of the Dpm difluoroborates (BODIPY) increases the intersystem spin crossing (ISC) and the triplet harvest whereas halogen atoms play no crucial role in fluorescence quenching of the systems with Zn(II) and Cd(II) complexing agents. Low fluorescence intensities of double Dpm moieties coordinated with the transition metal ions are provided by radiationless internal conversion suppressing photoemission with following ISC which is intensified in presence of halogens. BODIPY fluorescence undergoes direct ISC competition and quenching intensity depend on the kind and the number of halogens.

Monoiodo- and dibromsubstituted dipyrromethenes HL

This study focuses on the behavior of a new fluorescent marker for labeling individual biomolecules and staining cell organelles developed on a meso-substituted BODIPY platform. Boron(III) complex with meso-4-methoxycarbonylpropylsubstituted 3,3&rsquo, 5,5&rsquo, tetramethyl-2,2&prime, dipyrromethene has been synthesized and identified via visible, UV-, NMR- and MS-spectra X-ray. The behavior of fluorophore in solutions has been studied with various experimental techniques. It has been found that luminophore exhibits a high quantum yield (almost ~100&ndash, 75%) in the blue-green region (513&ndash, 520 nm) and has high photostability. In addition, biological analysis indicates that the fluorophore exhibits a tendency to effectively penetrate into cell membranes. On the other hand, the proposed BODIPY can be used to study the significant differences among a large number of pathogens of mycotic infections, as well as to visualize structural changes in the plasma membrane, which is necessary for the clearance of mammalian cells undergoing apoptotic cell death.

Photonics of complexes of p- and d-elements with dipyrromethenates is investigated. The role of substituents (their type and localization in the ligand) and of the medium in which dipyrromethenates are placed (solvents, gas mixtures, or solid matrices) is discussed as well as the effect of complexing agents on photonics of the examined complexes. The possibilities for dipyrromethenates application as liquid and solid state laser active media, sensor media for determining the oxygen concentration in a gas mixture, and photosensitizers for singlet oxygen generation in optical devices are presented.

The spectral luminescent properties of a series of zinc dipyrromethenate [Zn(dpm) 2 ] with alkyl-, phenyl-, meso-aza-, and halogen substituents in the ligand are studied in solutions in ethanol (neutral and acidified with hydrochloric acid). The stability of the complexes in proton-donor solvents in the ground and excited states is investigated, and quantum yields of laser-induced phototransformations are measured. In a number of cases, a relationship between the photochemical stability of the investigated dipyrromethenates and their properties in proton-donor media is found and discussed.

To date, synthesis and study of luminophores with practically significant sensory characteristics are the most promising direction of the oligopyrrole dyes chemistry. The results of sensory characteristics study of zinc(II) and boron(III) bis(dipyrromethenate)s to the various analytes presence in solutions and gas mixtures are discussed in this mini-review. The main aim of the mini-review is to examine the causes and mechanisms of the spectral signal of zinc(II) bis(dipyrromethenate)s to the presence of various nature analytes. The prospects of applications of fluorescent sensors based on zinc(II) and boron(III) bis(dipyrromethenate)s are discussed.

In this paper the interaction between tetramethyl-substituted BODIPY and bovine serum albumin (BSA) was studied using a spectroscopic approach (UV/vis spectrophotometry, spectrofluorimetry) and molecular docking. The fluorescence of tetramethyl-substituted BODIPY was found to substantially quenched in the presence of BSA. It was observed that BODIPY interacts with the BSA in the sub-domain site IIA of BSA. The BODIPY-BSA complex is formed due to the prevailing specific interactions.

In this paper, we report on the results of spectrofluorimetric study of new fluorescent sensor based on [Zn2L2] doped in ethyl cellulose. The sensor optical signal is based on the rapid fluorescence quenching in the presence of ethanol vapor. The ethanol vapor detection limit in a gas mixture by means of sensor based on [Zn2L2] doped in ethyl cellulose is 0.56 ppt. Being highly sensitive and selective to the ethanol vapor presence, instant in response and easy to use, the sensor may find an application for the monitoring of the content of ethanol vapor in the air at industrial and laboratory facilities. This sensor can serve as the basis of pocket gas analyzers for detecting ethanol in the exhaled air.

This paper presents the results of UV/vis, fluorescence, FT-IR, DOSY, and DFT study of a novel non-covalent supramolecular systems based on zinc(II) bis(dipyrromethenate)s ([Zn2L2]) with C60. It was found that zinc(II) bis(dipyrromethenate) forms stable supramolecular π-π-complexes ([Zn2L2(C60)4]) with C60. DFT calculations revealed stable complexation between [Zn2L2] and C60. The [Zn2L2(C60)4] LUMO energy levels are predominantly spread on the C60 unit and the HOMO energy levels are mainly spread on the [Zn2L2]. The photoinduced electron transfer testing by the substantial fluorescence quenching of the [Zn2L2] by non-covalent bonded C60 gives the positive result that shows prospects of the studying [Zn2L2(C60)4] as the active layers in solar energy conversion devices.

The effect of peripheral alkyl, aryl, and meso-aza substitution on the thermal stability of BODIPYs in an argon or oxygen atmosphere has been analyzed using thermogravimetric study results. It has been shown that an increase in the length of 2,6-alkyl substituents to seven carbon atoms is accompanied by the growth of BODIPY thermal stability by 80°C. The greatest increase in the destruction temperature of BODIPY (by 100°C) is attained via the introduction of phenyl groups in the 1,3,5,7-positions of its dipyrromethenmethene framework. meso-Aza substitution does not almost produce any effect on the thermal stability of BODIPY dyes. The BODIPY destruction beginning temperature decreases by 60–90°C in the presence of air oxygen. The thermal stability of BODIPY tends to decrease with reducing degree and symmetry of alkyl substitution in the dipyrromethene framework. A lower thermal stability of BODIPY in comparison with zinc(II) dipyrromethenates is due to the participation of fluorine atoms in intramolecular redox processes.

The results of investigation of the photostability and thermal degradation of B(III), Zn(II), Cd(II) complexes with monoiodo- and dibromosubstituted dipyrrins of the composition [BF2L] and [ML2] were presented. The processes of photo- and thermal degradation of complexes includes the initial stages of dye molecules dehalogenation. In general, the replacement of 4-iododipyrrin ligand by 5,5′-dibromo- and 4,4′-dibromosubstituted analogs in the composition of complexes [BF2L] and [ML2] promotes an increase in the photo- and thermal stability of the dyes. The replacement of the saturate hydrocarbon (cyclohexane) with the aromatic analogue (benzene) leads to a significant decrease in the photostability of [BF2L] and [ML2] because of polarization of the chromophore systems of dye molecules due to π-π stacking with aromatic solvent molecules. The thermal destruction start temperatures [ML2] and [BF2L] in the argon atmosphere range from 179 to 275 °C and strongly depend on the nature and efficiency of the participation of complexing and halogen atoms in intramolecular redox reactions. Complexes [BF2L], which showed the greatest photostability in solutions, differ the least thermal stability in the solid phase. The observed differences are due to the specific structural effects and different mechanisms of the photo- and thermal degradation processes under various environmental conditions.

Cadmium(II) chelates with 4-iodo-, 5,5´-, and 4,4´-dibromo-2,2´-dipyrromethenes (HL1, HL2, and HL3, respectively) with the composition of [CdL2] were synthesized. The influence of structural features of their molecules and properties of the medium on the characteristics of absorption and fluorescence spectra, and also on the thermodynamic stability constants in solutions was evaluated. The results of quantum chemical calculations revealed that the additional coordination interactions between the bromine atoms at the α-positions of dipyrromethene ligands and the complexing atom are possible in the molecular structure of α,α´- dibromosubstituted dipyrromethenate [Cd(L2)2] in contrast with β-halogenated analogues [Cd(L1)2] and [Cd(L3)2].

Photostability of B(III), Zn(II), Cd(II) complexes with monoiodo- and dibromosubstituted dipyrromethenes [BF2L] and [ML2] in benzene and cyclohexane solutions is studied. It is found that the mechanism of destruction of the dyes under UV radiation is based on participation of singlet oxygen generated by the excited triplet state of the dye. Singlet oxygen enters the oxidation reactions of the pigment molecules leading to accumulation of colorless products based on di-, monopyrrol, and smaller fragments. Initial stages of the process include the reactions of dehalogenation of the dye molecules and are accompanied by enhancement of the fluorescence of the formed alkyl-substituted dipyrromethenates. The photostability of boron complexes [BF2L] is up to 32 times higher as compared to that of [ZnL2] and [CdL2]. The replacement of 4-iododipyrromethene ligands in [BF2L] and [ML2] by 5,5'-or 4,4'-dibromo-substituted ligands increases photostability of the dyes. The stability of the dyes against UV irradiation substantially decreases in benzene with respect to cyclohexane due to enhancement of polarization of the chromophore systems of dipyrromethene ligands because of their solvation with benzene (π–π-stacking).

In this paper, the effect of meso-substituents nature and solvent properties on the photo- and thermal stability of BODIPYs, was studied. It was found that the replacement of the hydrogen atom in the methine bridge by CH3 group, carboxylic acid residues (CH2)nCOOH or their esters (CH2)nCOOCH3 (where n = 3, 4) significantly increases the photo- and thermal stability of meso-substituted dyes compared to meso-unsubstituted analog that is in good agreement with the results of NBO analysis. It has been established that the photooxidation process of dyes in solutions proceeds more efficiently in aromatic toluene (in ∼2–3 times) and, especially, in the electron donor DMSO (in ∼10 times) compared to non-polar cyclohexane, which is due to the specific solvation of dye molecules by aromatic and polar solvents.

The dipyrromethene derivatives as new chromo-fluorogenic chemosensors for quantitative detection and express analysis of Zn2+ ions were synthesized and structural characterized. The sensing process of dipyrromethene toward Zn2+ was evaluated by UV–vis and fluorescence spectroscopy, molar ratios plots, and DFT calculations. The complexation of Zn(AcO)2 with dipyrromethenes in DMF solution was accompanied by significant bathochromic and hyperchromic effects in the electronic absorption spectra due to the formation of [ZnL2] complex. The 1:2 (Zn:HL) binding mode was proposed on the basis of absorption and theoretical studies. The complexation constants (lgKo) of Zn(AcO)2 with dipyrromethenes are from 8.1 to 10.9, which implying the potential of dipyrromethenes to acts as selective chemosensors for Zn2+. It is shown for the first time that the hexamethyl-substituted dipyrromethene could recognize Zn2+ ions in DMF solution through significant (almost 100 times) “off–on” fluorescent response caused by Zn2+ and visible color change from yellow to bright green under UV irradiation induced by formation of [ZnL2]. Hexamethyl-substituted dipyrromethene had high selectivity towards Zn2+ ions over many environmentally relevant ions, and high sensitivity with the detection limit in nanomolar level (4·10–8 mol/L). In terms of the thermodynamic constant and the fluorescence response of the complexation reaction of [ZnL2], as well as the detection limit of Zn2+ ions, dipyrromethene HL2 surpasses many Zn2+ sensors known in the literature. Dipyrromethenes can be a tool for detecting Zn2+ ions with simple test strips.

Interaction of 4,4-difluoro-1,3,7,8-tetramethyl-2,6-disulfo-4-bora-3a,4a-diaza-s-indacene sodium salt (BODIPY, BP1) with bovine serum albumin (BSA) and human serum albumin (HSA) was investigated using spectral methods and molecular docking. It was shown that BP1 forms stable supramolecular complexes with BSA and HSA predominantly due to the specific interactions. Supramolecular complex formation was accompanied by strong fluorescence quenching of BP1 as a result of FRET. This effect could be used for the qualitative and quantitative detection of HSA in model physiological fluids. The detection limit of BSA and HSA were 0.26 and 0.05 mg·mL−1, respectively. The selectivity of BP1 fluorescence response to the co-presence of BSA and HSA in solution was demonstrated. The BP1 fluorescent probe was successfully used for the qualitative and quantitative detection of HSA in human urine samples. The obtained results indicated the capability of using BP1-based fluorescent sensors in clinical medicine for early detection of microalbuminuria and concomitant diseases.

Compounds with an open chain tetrapyrrole structure are mainly formed in plant and animal organisms during the catabolism of heme or other natural macrocyclic tetrapyrroles. Great success has been achieved in the development of synthetic open-chain analogs of natural tetrapyrroles with a successful combination of practically useful properties. Various combinations of several types of modifications in terms of the method, the nature of the attachment of the spacer and peripheral substituents make it possible to obtain compounds with the necessary set of properties, required for specific practical purposes. Bis(dipyrromethene)s are characterized by conformational isomerism. Depending on the preferred conformation, the bis(dipyrromethene) ligands form complexes of different structure and composition upon complexation with cations of some elements. Bright coloristic and fluorescent signals of the complexation processes of such ligands with metal cations are of great practical interest. The review discusses the possibilities of using bis(dipyrromethene)s as colorimetric and fluorescent sensors of amines and zinc, cadmium, and mercury cations. The review highlights prospects of using bis(dipyrromethene) complexes in various fields of medicine, laser technology, supramolecular chemistry, etc.

This paper presents the results of spectral-luminescence research of binuclear zinc(II) helicates with deca-, octa-, and tetramethylsubstituted 3,3′-bis(dipyrromethene)s ([Zn 2 L 2 ]) in binary mixtures of cyclohexane with m -, o - and p -xylene. Structure effects of [Zn 2 L 2 ], and aromaticity criteria of analytes (HOMA, NICS, μ ) on the fluorescence quenching efficiency of [Zn 2 L 2 ] in the presence of xylenes was considered. It was found that decamethyl substituted 3,3′-bis(dipyrromethenate)s compared to octa-, and tetramethylsubstituted-analogs shows the highest fluorescence sensitivity to the presence of aromatic compounds. Quantum-chemical modeling showed that [Zn 2 L 2 ] fluorescence quenching in the xylenes presence is caused by the formation of [Zn 2 L 2 A n ] (n = 1 or 2) supramolecular structures. High specificity of spectral-luminescent characteristics changing in the presence of xylenes provides the possibility of using [Zn 2 L 2 ] helicates as new fluorescent sensors for trace amounts (6.5–99 ppm) detection of methylbenzenes in organic media.

The complex formation of zinc(II) acetate with monoiodo- and dibromo-substituted dipyrromethenes in DMF at 298.15 K were studied by means of spectrophotometric titration. It was found that the process involves consecutive formation of heteroligand [ZnLOAc] and homoligand [ZnL2] complexes. The thermodynamic stability of halogenated zinc(II) dipyrrolylmethenates [ZnL2] was studied.

The spectral–luminescent, photophysical, and photochemical properties of dichloro-, dibromo-, and diiodo-derivatives of boron dipyrromethenate (BODIPY) have been studied, as well as the feasibility of generating singlet oxygen (1O2) via its photosensitization by the dihalogenated derivatives of BF2 dipyrromethene in solutions. Quantum yields of singlet oxygen have been determined using 1,3-diphenylisobenzofuran as the 1O2 trap. The lowest fluorescence quantum yields have been shown to correspond to the maximum yields of singlet oxygen. It has been found that the best 1O2 photosensitizer among the three test dihalotetraphenylaza- BODIPY is dibromotetraphenylaza-BODIPY, which in addition possesses the highest photostability. Diiodotetramethyl-BODIPY results in the singlet oxygen yield close to unity, but it has significantly lower photostability. The yield of singlet oxygen is affected by the solvent. Dibromtetraphenylaza-BODIPY and diiodotetramethyl-BODIPY may find use as a medium in photodynamic therapy and photocatalysis of oxidation reactions.

In this paper, detailed comparative analysis of the spectral properties of bis(BODIPY) dyes in various organic solvents: saturated aromatic hydrocarbons, homologous series of alcohols (CnOH, n = 2–4, 8, 10) and mixture of ethanol-glycerol with different viscosity was carried out. In bis(BODIPY) dimeric molecules, the BODIPY chromophore domains are linked by a methylene spacer at the 2,2-, 2,3-, or 3,3-positions (1, 2, and 3 respectively). The absorption spectra of the bis(BODIPY)s exhibit exciton splitting of band maxima. We showed that bis(BODIPY)s are sensitive to the polarity and acidity of media due to its structural features. The mechanism of fluorescence quenching of 1–3 in the series of alcohols are explained in detail. It has been established that the fluorescence quenching efficiency of dimeric dyes in alcohols is determined by both universal and specific interactions. The fluorescence quantum yield of bis(BODIPY)s is minimal in ethanol and increases in the alcohols homologous series due to a reduction in medium polarity and the stability of the bis(BODIPY)(Solv)2 supramolecular structures. In viscous ethanol-glycerol mixtures, fluorescence of 1–3 increases because of the limitation of the dye molecules conformational mobility. The results of the study allow us to predict the possibility of practical application of 1–3 as alcohols fluorescent sensors in various media.

It is well known that boron-dipyrromethene (BODIPY) dyes have a remarkable combination of photophysical and photochemical properties, which are significant for practical use. Unfortunately, the application of BODIPYs in optical devices and biosensorics is severely limited due to the aggregation quenching effect (ACQ), the effects of the internal filter and/or the formation of excimers. One way to prevent fluorescence quenching is to synthesize new molecules BODIPY with a highly complicated structural organization or hybrid systems based on them. But in this paper, we demonstrate that the introduction of simple aliphatic or aryl substituents into the ms-position of the BODIPY molecule is an effective way to control the aggregation in various states: thin mono- and multilayer Langmuir-Schaefer (LS) films, polymer films and concentrated solutions, including aqueous ones. The results of experimental studies of the aggregation behavior of BODIPYs (BDP1-BDP3) are in good agreement with the theoretical calculations data of di- and tetramers, as well as multilayer packing. This allows to adjust the spectral properties of luminophores to the most possible types of their real applications in practical areas.

Crystal solvates of zinc(II) 3,3′,5,5′-tetramethyl-4,4′-dibromo-dipyrromethenate [ZnL2] form supramolecular complexes [ZnL2(C2H5OH)2] and [ZnL2(DMF)2] with molecules of ethanol and DMF. Such complexes are stable up to ∼ 150 and 111 °C, respectively. According to the quantum chemical calculations, [ZnL2(DMF)2] is formed due to the additional coordination of molecular ligands by the zinc atom (Znδ+ ⟵: O). In the case of [ZnL2(C2H5OH)2], along with weak coordination interactions of the hydroxyl group oxygen with the zinc ion, the main contribution to the suprastructure formation is made by hydrogen bonds (C2H5OH ⟵ :N≤), which makes both the destruction onset temperature and the total enthalpy (ΔHΣ) of the intermolecular interactions in [ZnL2(C2H5OH)2] much higher than in [ZnL2(DMF)2]. The obtained results are interesting for the development of new [ZnL2] fluorescent sensors of N- and O-containing analytes.

The off-on fluorescent chemosensor based on the bis(2,4,7,8,9-pentamethyldipyrrolylmethene-3-yl)methane for detection of Cd2+ and Hg2+ ions was obtained and its metal ion sensing properties were investigated. The bis(dipyrrin) exhibited remarkably fluorescence enhancement (150- and 40-fold) to Cd2+ and Hg2+ ions, respectively, with significant color change on the background of other metal ions in propanol-1/cyclohexane (1:30) binary mixture. Consequently, it can be used as a “naked eye” indicator with an obvious color change from yellow-orange to orange-green color upon the addition of Cd2+ and Hg2+. The fluorescent response mechanism of bis(dipyrrin) to Cd2+ and Hg2+ was based on the fluorescence enhancement effect upon complexation (CHEF) due to formation of a metal–ligand (2:2) complex [M2L2]. The detection limit of Cd2+ and Hg2+ ions was 2 × 10–9 and 1.7 × 10–8 M ions, respectively.

It was found that 3,3′-, 2,3′- and 2,2′-zinc(II) bis(dipyrromethenate)s ([Zn2L2]) form stable supramolecular complexes with aromatic and aliphatic amines (X - pyridine (Py), N,N-dimethylmethanamide (DMF), diethylamine (DEA) and triethylamine (TEA)) of the composition [Zn2L2(X)n]. Composition, stability and spectral-luminescent properties of the [Zn2L2(X)n] crystal solvates were studied by means of FTIR, PXRD, thermal, mass spectral, absorption, and fluorescence analyses. Spectroscopic studies showed that the quantum yield (φ) of [Zn2L2(Х)n] in cyclohexane is much lower (to ∼ 1.4–4.0 times) than φ for the [Zn2L2]. Crystal solvates are stable up to a temperature ∼367.35–427.55 K. It is demonstrated, that the high interactions energies (Zn N) in [Zn2L2(X)n] supramolecular complexes are the main cause of the fluorescence quenching of [Zn2L2] luminophores in the presence of electron-donor molecules. The obtained results are of interest for the development on the basis of [Zn2L2] of a new fluorescent sensors of the electron donor molecules.

It was proposed new highly sensitive «ON–OFF» fluorescent amines trace amounts (1.6x10−6–9.3x10−5 mol/L) sensors in organic media based on binuclear zinc(II) helicates with 2,2′-, 2,3′- and 3,3′- bis(dipyrromethene)s ([Zn2L2]). The results of fluorescence spectral studies of [Zn2L2]in binary mixtures of cyclohexane with amines (pyridine, diethylamine and trimethylamine) were presented. The influence of bis(dipyrromethene) ligands isomerism and electron-donating ability of N-containing co-solvent on the fluorescence quenching efficiency of [Zn2L2] in the presence of amines was discussed. It was determined, that the zinc(II) 3,3′-bis(dipyrromethenate) exhibits the highest fluorescence sensitivity in the amines presence in comparison with 2,3′- and 2,2′-analogs.