Gürkan Keşan

University of South Bohemia in České Budějovice · Faculty of Science

This work examines the influence of applied external voltage in bulk electrolysis on the excited‐state properties of 8′‐apo‐β‐carotenal in acetonitrile by steady‐state and ultrafast time‐resolved absorption spectroscopy. The data collected under bulk electrolysis were compared with those taken without applied voltage. The steady‐state measurements...

Non-covalent functionalization of single wall carbon nanotubes (SWCNTs) has been conducted using several binding agents with surface π-interaction forces in recent studies. Herein, we present the first example of non-covalent functionalization of sidewalls of SWCNTs using thienothiophene (TT) derivatives without requiring any binding agents. Synthe...

The Cl replacement reaction of octachlorocyclotetraphosphazene, N4P4Cl8 (1), with two equimolar amounts of N-(4-fluorobenzyl)-N′-methylpropane-1,3-diamine led to the formation of 4,4,8,8-tetrachloro-2-trans-6-bis-N-(4-fluorobenzyl)-N′-methylpropane-1,3-diamino-cyclotetraphosphazene (2). The reaction of 2 with excess sodium 2,2,3,3-tetrafluoro-1,4-b...

A solution-processed organic photodiodes can function as thin-film alternative for solid-state photosensor in various optoelectronic applications due to the physical and chemical tuneability. In spite of their unique structural, optical, and electronic properties, the development of BODIPY based organic phodiodes has lagged behind that of other lum...

Novel fluorescent anthracene-decorated cyclotri- and cyclotetraphosphazenes (5 and 6) are designed and synthesized, and their chemosensor behaviors against nitroaromatic compounds are examined by UV/Vis and fluorescence spectroscopies for addressing the sensors with cyclophosphazenes for 2,4,6-trinitrotoluene detection. The fluorescence intensities...

The synthesized and sensing capability of two novel azaindole substituted mono and distyryl BODIPY dyes against bisulfate anion were reported. Structural characterizations of the targeted compounds were conducted by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, ¹H and ¹³C NMR spectroscopies. Photophysical prope...

RC-LH1-PufX complexes from a genetically modified strain of Rhodobacter sphaeroides that accumulates carotenoids with very long conjugation were studied by ultrafast transient absorption spectroscopy. The complexes predominantly bind the carotenoid diketospirilloxanthin, constituting about 75% of the total carotenoids, which has 13 conjugated C=C b...

We used ultrafast transient absorption spectroscopy to study excited-state dynamics of the keto-carotenoid fucoxanthin (Fx) and its two derivatives: 19’-butanoyloxyfucoxanthin (bFx) and 19’-hexanoyloxyfucoxanthin (hFx). These derivatives occur in some light-harvesting systems of photosynthetic microorganisms and their presence is typically related...

In this study, the subphthalocyanine-borondipyrromethene conjugates have been successfully designed and synthesized. The novel compounds were fully characterized by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, 1H, and 13C NMR spectroscopy. The photophysical properties of the conjugates were investigated by mea...

The halogen and solvent effects on the structure of 4-bromo-2-halogenobenzaldehydes [C7H4BrXO; X = F (BFB), Cl (BCB) or Br (BBB)] were investigated by the density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The B3LYP functional and HF and MP2 levels of theory were used with the 6-311+G(3df,p) or aug-cc-pVDZ...

Conformers of N-methacryloyl-(L)-glutamic acid (MAGA, C9H13NO5) in the gas phase, benzene or methanol environment were searched by the density functional theory (DFT) and time-dependent DFT. Selected conformational isomers based on potential energy surface analysis were studied by considering the structural and electronic properties. B3LYP function...

The structure of 1-formyl-3-phenyl-5-(4-isopropylphenyl)-2-pyrazoline synthesized as single was investigated by FTIR, NMR, XRD. Experimental data were complemented by quantum mechanical calculations. XRD data show that the compound crystallizes in the triclinic system (P−1) via trans isomer (a = 6.4267(4), b = 10.9259(12), c = 12.4628(9) Å and α =...

Violaxanthin-chlorophyll a protein (VCP) from Nannochloropsis oceanica is a Chl a-only member of the LHC family of light-harvesting proteins. VCP binds carotenoids violaxanthin (Vio), vaucheriaxanthin (Vau), and vaucheriaxanthin-ester (Vau-ester). Here we report on energy transfer pathways in the VCP complex. The overall carotenoid-to-Chl-a energy...

In order to estimate the possible structure of the unknown carbonyl carotenoid related to isofucoxanthin from Chromera velia denoted as isofucoxanthin-like carotenoid (Ifx-l), we employed steady-state and ultrafast time-resolved spectroscopic techniques to investigate spectroscopic properties of Ifx-l in various solvents. The results were compared...

A novel Cu/Pd heterometallic cyanide-bridged complex of 3-methylpyridazine (3-mpdz), [Cu(3-mpdz)2Pd(µ-CN)4]n, was synthesized and its structure was characterized by FT-IR, Raman, single-crystal X-ray diffraction and thermal/elemental analysis techniques. The conformers, optimized geometric parameters, normal mode frequencies and corresponding vibra...

Two carotenoids with aryl rings were studied by femtosecond transient absorption spectroscopy and theoretical computational methods, and the results were compared with those obtained from their non-aryl counterpart, β-carotene. Although isorenieratene has more conjugated C=C bonds than β-carotene, its effective conjugation length, Neff, is shorter...

We report on energy transfer pathways in the main light-harvesting complex of photosynthetic relative of apicomplexan parasites, Chromera velia. This complex, denoted CLH belongs to the family of FCP proteins and contains chlorophyll (Chl) a, violaxanthin, and the so far unidentified carbonyl carotenoid related to isofucoxanthin. The overall carote...

FT-IR and Raman spectra of 1-cyclopentylpiperazine (1cppp) have been experimentally examined in the region of 4000-200 cm−1. The optimized geometric parameters, conformational equilibria, normal mode frequencies and corresponding vibrational assignments of 1cppp (C9H18N2) are theoretically examined by means of B3LYP hybrid density functional theory...

FT-IR and FT-Raman spectra of 1-cyclopropylpiperazine (1cppp) are experimentally examined in the range 4000-200 cm−1. The optimized geometric parameters, conformational equilibria, normal mode frequencies and corresponding vibrational assignments of 1cppp C7H14N2 are theoretically examined by means of B3LYP hybrid density functional theory (DFT) wi...

Infrared and Raman spectra of 1-formylpiperazine (1-fp) have been recorded in the region of 4000-50cm(-1). The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1-fp (C5H10N2O) have been examined by means of Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) meth...

Excited-state properties of the carbonyl carotenoid monomeric and aggregated 8'-apo-β-carotenal were studied by means of femtosecond transient absorption spectroscopy. For 8'-apo-β-carotenal monomers, the polarity-dependent behavior characteristic of carotenoids with conjugated carbonyl group was observed. While in n-hexane the S1 lifetime of 8'-ap...

FT-IR and Raman spectra of 1-pyrrolidino-1-cyclopentene (1py1cp) were experimentally reported in the region of 4000-10cm(-1) and 4000-100cm(-1), respectively. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1py1cp (C(9)H(15)N) were theoretically examined by means of the B3LYP hybrid density f...

The optimized structural parameters (bond lengths, bond and dihedral angles), conformational equilibria and normal mode frequencies and corresponding vibrational assignments of 4-(1-Pyrrolidinyl)piperazine (4-pypp) have been examined by means of B3LYP hybrid density functional theory (DFT) method with 6-31++G(d,p) basis set. Furthermore, reliable v...

New metal halide complexes in the form of M(pp)(2)Cl(2) (where pp=1-phenylpiperazine and M=Pd or Hg) have been prepared for the first time and their FT-IR and FT-Raman spectra are reported in the region of 4000-10 cm(-1) and 4000-50 cm(-1), respectively. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assig...