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Abstract: Two novel spirobifluorene-cored dendrimers containing polyphenylene dendrons with the carbazole (spiro-Cz) and cyano surface groups (spiro-CN) were synthesized and characterized. Both the dendrimers show good solubility in common organic solvents. Spiro-Cz is amorphous even when it is obtained directly from organic solvents and an extremely high glass transition temperature of 332 °C is detected. These dendrimers can be reversibly oxidized and reduced in electrochemical measurements. They are blue fluorescent with small red-shift in solid film absorption and fluorescence spectra. These advantageous merits are suggested to benefit from the combined contribution from the spirobifluorene core and the bulky polyphenylene dendrons. They were used as emitting layer to fabricate organic light-emitting diodes (OLEDs). Deep-blue electroluminescence was obtained for both dendrimers devices. [Copyright &y& Elsevier]

Abstract: Two covalently linked boron dipyrromethene (BODIPY) dyads containing meso-phenyl BODIPY and meso-furyl BODIPY units connected via meso-meso and meso-α positions were synthesized by a Pd(0) coupling reaction. The dyads are freely soluble in common organic solvents and their structures were confirmed by HR-MS, 1D and 2D NMR techniques. Absorption studies indicate that the meso-aryl BODIPY and the meso-furyl BODIPY absorb in two different regions and that the meso-furyl BODIPY absorbs at lower energy compared to the meso-aryl BODIPY. The steady state fluorescence studies carried out by exciting the meso-aryl BODIPY unit clearly indicated an efficient singlet–singlet energy transfer from the meso-aryl BODIPY unit to meso-furyl BODIPY unit in both dyads. Furthermore the meso-α linked BODIPY dyad (ϕ f =0.41) is more fluorescent than its corresponding BODIPY monomers whereas the meso-meso linked BODIPY dyad (ϕ f =0.017) is weakly fluorescent. This unexpected observation was tentatively attributed to the restricted rotation of the BODIPY units in the meso-α linked dyad resulting in enhancement of radiative transitions. The time-resolved fluorescence study also indicated that meso-α linked BODIPY dyad is more fluorescent with singlet state lifetime of 3.7ns. The DFT studies carried out on dyads are in agreement with the experimental observations. [Copyright &y& Elsevier]

Abstract: Paper introduces new heteroazulene derivative, 10-methoxy-6-methyl-6H-5,6,7-triazadibenzo[f,h]naphtho[3,2,1-cd]azulene (MMTNA), including chemical aspects of its synthesis likewise optical absorption and fluorescence spectra measured in several organic solvents of different polarity. The obtained experimental results are subjected to the quantum-chemical analysis based on DFT/TDDFT/PCM calculations at the B3LYP/6-31+G(d,p) level of theory. MMTNA demonstrates insignificant solvatochromism of both first absorption and fluorescence bands caused mainly by a weakly polar feature of its ground and lowest excited states. Despite this the emission bands appears to be considerably red shifted with respect to relevant first absorption bands resulting thus to a substantial Stokes shift. Its origin is dominated by the conformational relaxation in the excited state whereas the solvent relaxation has practically no influence on the emission spectra. Low sensitivity to the host environment makes MMTNA dye perspective for a number of applications, particularly in those cases when a high stability of the emission wavelength (color) is demanded. [Copyright &y& Elsevier]

Abstract: Two rhodanine complex merocyanine dyes 9a and 9b were synthesized and their structures were confirmed by 1H NMR, IR, MS, HRMS and UV–Vis spectra. From the spectral properties of the two dyes, it could be found that the λ max of the dyes showed hypsochromic shifts with the increase of permittivity in protonic solvents, and bathochromic shifts with the increase of refractive index in non protonic solvents. The interactions of two dyes with DNA or BSA were also studied under physiological conditions. The results showed that the quantum yield of DNA-dye 9a was up to 29.5 times compared with free dye 9a. Dyes 9a and 9b were researched in Photodynamic Therapy (PDT) as well. It was demonstrated that supplementation of dye 9a or 9b as photosensitizers for PDT in K562 cells decreases the survival rate. [Copyright &y& Elsevier]

Abstract: Two novel tetraester- and PAMAM-branched perylene diimides were synthesized and configured as “fluorophore-spacer-receptor” systems based on photoinduced electron transfer. Due to their long alkylester and alkylamine terminal groups the examined compounds were well soluble in organic solvents. Photophysical characteristics of the dyes were investigated in DMF and water/DMF (1:1, v/v) solution. The ability of the synthesized perylene diimides to detect cations was evaluated by the changes in their fluorescence intensity in the presence of metal ions (Zn2+, Co2+, Cu2+, Fe3+, Pb2+, Hg2+, Ag+ and Ni2+) and protons. The dyes under study displayed “off–on” switching in its fluorescence as a function of pH, which is attributed to disallowing photoinduced electron transfer from the receptor moiety to the fluorophore. PAMAM-branched dye displayed a good pH sensor activity (FE = 6.4), however the pH sensing ability of tetraester was substantially higher (FE = 184). In the presence of Cu2+ and Pb2+ ions tetraester quenched its fluorescence intensity (FQ = 22 and 12 respectively), while PAMAM-branched dye enhanced its fluorescence intensity with pronounced selectivity to Cu2+ and Fe3+ (FE = 3.2 and 4.9, respectively). The results obtained indicate the potential of the novel compounds as fluorescent detectors for metal ions with pronounced selectivity towards Cu2+, Pb2+ and Fe3+ ions and highly efficient “off –on” pH switches, especially a tetraester-branched perylene diimide. [Copyright &y& Elsevier]

Abstract: The novel optically active Pc-4 (neutral) and Pc-5 (ionic), zinc(II) phthalocyanines having four N-benzyl protected l-prolinol unit were synthesized. l-prolinol has binucleophilic character and can be anchored to phthalonitrile derivative from both nitrogen and oxygen atoms. In order to overcome this problem and to enhance the solubility of phthalonitrile (S)-(-)-3 and the target phthalocyanines, the nitrogen atom of l-prolinol was first protected with benzyl chloride. All the compounds were characterized by 1H and 13C NMR, MALDI–TOF MS, IR, UV–vis, and Circular Dichroism (CD) spectroscopy. Pc-4 is highly soluble in most common organic solvents, whereas ionic Pc-5 is soluble in water. The CD results showed that the chiral information was transferred from the peripheral chiral l-prolinol side chains to the phthalocyanine chromophore at the molecular level. [Copyright &y& Elsevier]

Abstract: Two novel BODIPY dyes were synthesized, and their fluorescence characteristics studied in different solvents. Both dyes were extremely sensitive to solvent polarity. Their fluorescence intensities were very low in DMSO but increased more than 80 times in chloroform; similar behaviour was found in fluorescence quantum yield, which was enhanced ∼60-fold. Both dyes displayed fluorescence enhancement with bovine serum albumin, which illustrated that the two probes were very sensitive to polarity change and, therefore, may be valuable as microenvironment-sensitive probes in biochemical research. [ABSTRACT FROM AUTHOR]

Abstract: Zinc (II) phthalocyanines carrying four poly(aryl benzyl ether) dendritic substituents with terminal cyano and carboxylic acid functionalities were synthesized and characterized using elemental analysis, 1H NMR, IR, UV–vis and matrix-assisted laser-desorption ionization time-of-flight spectra. Phthalocyanines with terminal cyano groups were essentially non-aggregated in common organic solvents whilst the aqueous aggregation tendency of those which contained terminal carboxylic acid groups decreased with increasing size of the dendron. Photoinduced electron transfer in these compounds was investigated using a fluorescence quenching method, employing both neutral and cationic quenchers. Upon excitation of the dendritic subunits in DMSO, the cyano compounds underwent intermolecular energy transfer from the excited dendritic subunits to the phthalocyanine core which acted as an energy trap. [Copyright &y& Elsevier]

Abstract: A series of five symmetrical and four unsymmetrical diaryl substituted diketo-pyrrolo-pyrroles was synthesized; two unsymmetrical derivatives are reported for the first time. The relationship between the theoretical excitation energies of the S0 → S1 transition, computed by time dependent density functional theory and the experimental positions of 0–0 vibronic bands in the visible absorption (or fluorescence excitation) spectra was studied. Experimental data were obtained from either solution or from low temperature organic solvent glass, in which the progressions of the vibrational structure enabled correct assignment of vibronic sub-bands in some cases. Theoretical calculations predicted that a linear bathochromic and hyperchromic shift would accompany substitution of each phenyl in the parent 3,6-diphenyl-2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione by providing a more extensively conjugated aryl centre (2-naphthyl, biphenyl, stilbenyl) for the ensuing planar derivatives. Qualitatively, the experimental bathochromic shifts of the 0–0 vibronic sub-bands were in exact agreement with theory, whilst hyperchromic shifts were affected by the very low solubility of the planar, symmetrical derivatives. Deviations from this ideal behaviour were observed for non-planar derivatives (aryl = stilbenyl or 1-naphthyl), for which the dihedral angles describing the aryl, out-of-plane torsions were probably underestimated by DFT. [Copyright &y& Elsevier]

Abstract: Highly soluble perylene diimide derivatives with symmetrical and unsymmetrical secondary, tertiary alkyl side chains were synthesized and their photophysical properties, redox potentials and thermal stabilities were measured and compared with previously reported 1-pentylhexyl substituted swallow-tailed perylene diimide. Diasteroisomers of the novel, unsymmetrical swallow-tailed substituted perylene diimide compound could not be detected using low temperature NMR spectroscopy. The novel dyes were soluble in a range of organic solvents indicating potential for photo-electronic applications and photocatalytic reactions. Two dyes were not only soluble in organic solvents but also showed solubility in aqueous media as the hydrochloride salt, thus offering potential use in biological applications. [Copyright &y& Elsevier]

Abstract: The synthesis of novel, symmetrical, hexadecasubstituted phthalocyaninatozinc(II) bearing eight, fluorinated phenoxy groups in peripheral positions and eight, non-peripheral hexyloxy groups as well as their related unsymmetrical derivatives is described. The compounds were characterized by 1H NMR, GC–MS, UV–vis and IR. The synthesized ZnPc complexes possess excellent solubility in various organic solvents such as CH2Cl2, THF, acetone and ethyl acetate and do not readily aggregate in solution. The new complexes show interesting luminescence properties in different organic solvents. [Copyright &y& Elsevier]