Petr Zimcik

Charles University in Prague, Praha, Praha, Czech Republic

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Publications (49)149.96 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A series of zinc complexes of phthalocyanine, naphthalocyanine and their aza-analogues with alkylsulfanyl substituents was synthesized and characterized by UV-vis and MCD spectroscopy, and their redox properties were investigated using CV, DPV, and SWV approaches as well as spectroelectrochemical methods. Aggregation, photostability, singlet oxygen production, and fluorescence quantum yields of the target complexes were studied as a function of the stepwise substitution of the aromatic C-H fragments by nitrogen atoms. The electronic structure and vertical excitation energies of the target compounds were probed by DFT-PCM and TDDFT-PCM approaches. Introduction of additional nitrogens into the structure leads to a hypsochromic shift of the Q-band and makes the macrocycle strongly electron deficient and more photostable. The impact on the photophysics is limited. The relationships between the type of macrocycle and the studied properties were defined.
    Dalton Transactions 06/2015; DOI:10.1039/C5DT01863C · 4.10 Impact Factor
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    ABSTRACT: A synthesis procedure for heteroatom-substituted tetra(3,4-pyrido)porphyrazines that absorb light near 800 nm was developed. Based on the observed relationships between the structure and photophysical parameters, a novel highly photodynamically active (IC50 = 0.26 μM) compound was synthesized and biologically characterized.
    Organic & Biomolecular Chemistry 04/2015; 13(20). DOI:10.1039/c5ob00651a · 3.49 Impact Factor
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    ABSTRACT: The intramolecular charge transfer (ICT), which is a pathway for excited state relaxation, was studied on the newly synthetized zinc (II) complexes of tetrapyrazinoporphyrazines bearing one fixed donor (i.e., a dialkylamino substituent). The rest of the peripheral substituents on the core were designed with respect to their different electronic effects (OBu, neopentyl, StBu, COOBu). The photophysical (singlet oxygen and fluorescence quantum yields) and electrochemical (reduction potentials) properties were determined and compared within the series and with compounds that did not contain a donor moiety. The ICT efficiency correlated well with both the electron-deficient character of the core and the Hammett substituent constants p. The most efficient ICT was observed for the core with the most electron-accepting substituent (COOBu), and the lowest ICT efficiency was detected for the least electron-deficient core (substituted by OBu). Titration of DMSO solutions of target compounds with H2SO4 indicated that basicity of the azomethine bridges was largely influenced by character of the peripheral substituents while the dialkylamino donor center remained nearly unaffected. Further, protonation of donor nitrogen caused partial restoration of fluorescence quantum yield (increase up to 90 times) due to blocking of ICT. The results implied that the ICT efficiency was strongly dependent on the electron-accepting properties of the core whose properties can be readily affected by suitable selection of peripheral substituents
    Dalton Transactions 03/2015; 44(15). DOI:10.1039/C5DT00400D · 4.10 Impact Factor
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    ABSTRACT: Novel zinc, magnesium and metal-free octasubstituted phthalocyanine photosensitizers bearing triethylammonioethylsulfanyl substituents in the peripheral or non-peripheral positions were synthesized and investigated for their photophysical properties (ΦΔ value up to 0.91,λmax up to 750 nm) and photodynamic anti-cancer activity. The photodynamic treatment of 3T3, HeLa, SK-MEL-28, and HCT 116 cancer cells revealed that the magnesium complexes were not active (IC50 〉100 μM), whereas the IC50 values of the zinc complexes typically reached values in the submicromolar concentrations with low toxicity in the dark (TC50 ∼ 1500 μM). The subcellular changes upon photodynamic treatment of the HeLa cells indicated that the studied photosensitizers induced damage primarily to the lysosomes which was followed by a relocalization and damage to other organelles. The time-lapse morphological changes along with the flow cytometry and caspase activity measurements indicated a predominant involvement of necrosis like cell death.
    Journal of Medicinal Chemistry 01/2015; 58(4). DOI:10.1021/jm5014852 · 5.48 Impact Factor
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    ABSTRACT: A series of low-symmetry ZnII, MgII, and metal-free porphyrazine derivatives with one 1,2,5-chalcogenadiazole ring (with S, Se or Te) and three pyrazines bearing tert-butylsulfanyls were synthesized. The absorption maxima of ZnII complexes lay at 660, 674, and 707 nm for S, Se, and Te, respectively, indicating increasing contribution of the 1,2,5-chalcogenadiazole rings to the π-electronic system. Photophysical studies revealed that introduction of Se as a chalcogen and ZnII as a central metal causes an increase in the singlet oxygen quantum yield, reaching a value of 0.81, whereas the combination of S and MgII gives only 0.39. This takes place on the account of the fluorescence quantum yields that differ significantly from 0.072 (ZnII+Se) to 0.51 (MgII+S). These results demonstrated the two-dimensional heavy atom effect combining the role of the chalcogen (first dimension) as well as the central metal (second dimension). Attempts to prepare oxygen-containing isologues led to the formation of an unexpected side product.
    European Journal of Organic Chemistry 12/2014; 2015(3). DOI:10.1002/ejoc.201403329 · 3.15 Impact Factor
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    ABSTRACT: Conditions for the Newman-Kwart rearrangement of phenols into thiophenols were investigated in relation to the bulkiness of substituents at the 2 and 6 positions of the starting phenol derivative with an emphasis on eliminating side reactions. Thiophenols with different 2,6-disubstitution patterns (including hydrogen, methyl, isopropyl or tert-butyl groups) were used for the synthesis of 5,6-bis(arylsulfanyl)pyrazine-2,3-dicarbonitriles that underwent cyclotetramerization leading to the corresponding zinc tetrapyrazinoporphyrazines (TPyzPz), aza-analogues of phthalocyanines. Several methods for the cyclotetramerization were attempted to eliminate problematic side reactions such as the exchange the arylsulfanyls with alkoxides from the initiator. Magnesium butoxide was found as the most suitable cyclotetramerization agent and afforded TPyzPzs in reasonable yields of approximately 30 % under mild conditions. The varying arrangements of the peripheral substitutions resulting from the different bulkiness of the substituents were demonstrated by the X-ray structures of the pyrazine-2,3-dicarbonitriles. The prepared zinc arylsulfanyl TPyzPzs showed an absorption maximum at a Q band over 650 nm, fluorescence quantum yields between 0.078-0.20, and singlet oxygen quantum yields ranging 0.58-0.69. TPyzPzs with isopropyl groups were found to be the best derivatives in this series as they combined facile cyclotetramerization, no aggregation and good photophysical properties, which makes them potentially suitable for photodynamic therapy.
    The Journal of Organic Chemistry 02/2014; 79(5). DOI:10.1021/jo402791c · 4.64 Impact Factor
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    ABSTRACT: A series of unsymmetrical tetrapyrazinoporphyrazines (TPyzPzs) from the group of azaphthalocyanines with one peripherally attached amino substituent (donor) were synthesized, and their photophysical properties (fluorescence quantum yield and singlet oxygen quantum yield) were determined. The synthesized TPyzPzs were expected to undergo intramolecular charge transfer (ICT) as the main pathway for deactivating their excited states. Several structural factors were found to play a critical role in ICT efficiency. The substituent in the ortho position to the donor center significantly influences the ICT, with tert-butylsulfanyl and butoxy substituents inducing the strongest ICTs, whereas chloro, methyl, phenyl, and hydrogen substituents in this position reduce the efficiency. The strength of the donor positively influences the ICT efficiency and correlates well with the oxidation potential of the amines used as the substituents on the TPyzPz as follows: n-butylamine < N,N-diethylamine < aniline < phenothiazine. The ICT (with conjugated donors and acceptors) in the TPyzPz also proved to be much stronger than a photoinduced electron transfer in which the donor and the acceptor are connected through an aliphatic linker.
    Physical Chemistry Chemical Physics 02/2014; DOI:10.1039/c3cp54731k · 4.20 Impact Factor
  • Jan Svec, Petr Zimcik
    15th Brazilian Meeting on Organic Synthesis; 12/2013
  • Cidlina A., Novakova V., Zimcik P.
    15th Brazilian Meeting on Organic Synthesis; 12/2013
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    ABSTRACT: Newly synthesized zinc phthalocyanine bearing sixteen quaternized imidazolyl moieties on the periphery displays high water-solubility, lack of aggregation and high singlet oxygen quantum yield in water (ΦΔ > 0.33). The in vitro tests indicated excellent anticancer photodynamic activity (EC50 = 36.7 nM) and low dark toxicity to non-cancerous cells (TC50 = 395 μM).
    Chemical Communications 09/2013; 49(95). DOI:10.1039/c3cc44609c · 6.72 Impact Factor
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    ABSTRACT: Light up a red crown: Chelation of sodium and potassium cations by aza[15]crown-5 switches on strong red fluorescence in azaphthalocyanines. It is due to an inhibition of ultrafast intramolecular charge transfer by coordination of the cations to donor center. Sodium cations fit well into a cavity of the recognition moiety, while potassium forms supramolecular assemblies of azaphthalocyanines with 1:2 stoichiometry.
    Chemistry - A European Journal 04/2013; 19(16). DOI:10.1002/chem.201300079 · 5.70 Impact Factor
  • Chemistry 04/2013; 19(16):4953-4953. DOI:10.1002/chem.201390053 · 5.70 Impact Factor
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    ABSTRACT: The formation of self-assemblies between CdSe quantum dots (QDs) and Zn phthalocyanines (Pc) and azaphthalocyanines (AzaPc) bearing alkylsulfanyl substituents and the photophysical properties of these assemblies were studied using both steady-state and time-resolved luminescence/absorption spectroscopy. The formation of the self-assemblies was accompanied by a blue shift of the Q band of the dyes and by a quenching of the CdSe QDs luminescence. The largest spectral shift of the Q-band was approximately 7 nm and was observed for pentan-3-ylsulfanyl-functionalised phthalocyanine (). Assuming a 1 : 1 stoichiometry, the calculated binding constant was 4 × 10(4) M(-1). Pc substituted with the bulky tert-butylsulfanyl groups () exhibited a smaller shift of the Q band. The quenching of the CdSe QDs luminescence by was more effective than that observed for . The results indicated that the luminescence quenching may be due to a photoinduced charge transfer between or and the CdSe QDs. In contrast, the AzaPc () with the same substituents as had little effect on the QDs luminescence. For all cases, we found an inefficient resonance energy transfer between the attached dyes and the CdSe QD. The formation of the self-assemblies had negligible effects on the photogeneration of the singlet oxygen, O(2)((1)Δ(g)), that was fully controlled only by the absorption of the light by the macrocycles.
    Photochemical and Photobiological Sciences 01/2013; 12(5). DOI:10.1039/c2pp25348h · 2.94 Impact Factor
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    ABSTRACT: a b s t r a c t A series of zinc phthalocyanines and corresponding aza-analogues azaphthalocyanines substituted with peripheral 2,6-diisopropylphenoxy substituents containing different functional groups (Br, OCH 3 , and OH) were synthesized and their photophysical properties were investigated. UVevis and 1 H NMR analyses confirmed the non-aggregation behavior of the prepared complexes in most organic solvents. All investigated compounds showed good photophysical and photochemical properties in THF and DMF with F F values in the range of 0.22e0.44 and F D values ranging between 0.42 and 0.57. Hydroxylated compounds showed good solubility in polar solvents including ethanol, methanol, acetone and even in aqueous ethanol mixtures. Absorption spectra in aqueous ethanol indicated presence of only monomers even at very low ethanol content in water (0.5% of ethanol in water). Despite this, no fluorescence occurred from approximately 50% of ethanol in water suggesting presence of aggregates that do not differ from monomers in a shape of absorption spectra.
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    ABSTRACT: Intramolecular charge transfer (ICT) was studied on a series of magnesium, metal-free and zinc complexes of unsymmetrical tetrapyrazinoporphyrazines and tribenzopyrazinoporphyrazines bearing two dialkylamino substituents (donors) and six alkylsulfanyl or aryloxy substituents (non-donors). The dialkylamino substituents were responsible for ICT that deactivated excited states and led to considerable decrease of fluorescence and singlet oxygen quantum yields. Photophysical and photochemical properties were compared to corresponding macrocycles that do not bear any donor centers. The data showed high feasibility of ICT in the tetrapyrazinoporphyrazine macrocycle and significantly lower efficiency of this deactivation process in the tribenzopyrazinoporphyrazine type molecules. Considerable effect of non-donor peripheral substituents on ICT was also described. The results imply that tetrapyrazinoporphyrazines may be more suitable for development of new molecules investigated in applications based on ICT.
    Dalton Transactions 07/2012; 41(38):11651-6. DOI:10.1039/c2dt31403g · 4.10 Impact Factor
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    ABSTRACT: A series of azaphthalocyanines (AzaPc) bearing one, two, four or eight isopropylidene-protected galactosyl units was prepared by azide-alkyne click reaction or by classical Pc template cyclotetramerization of the corresponding dicyanopyrazine and AzaPc properties important for photodynamic therapy were compared. All compounds absorbed at long wavelengths (above 650 nm) and belonged to strong singlet oxygen producers (Φ(Δ) = 0.58-0.64) retaining significant fluorescence emission (Φ(F) = 0.026-0.23). The only exception was the compound with four isopropyliden-protected galactosyl units where partial aggregation was observed. Removal of protecting groups increased the polar character of all AzaPc. However, only AzaPc bearing eight galactoses was found to be water-soluble (105 mg mL(-1)) but noticeably aggregated in water as well as in organic solvents (DMF, DMSO). Amphiphilic AzaPc bearing one deprotected galactose was incorporated into the lipidic bilayer of liposomes in a nonaggregated form. Liposomes may therefore be a suitable delivery system for this amphiphilic photosensitizer.
    Dalton Transactions 07/2012; 41(35):10596-604. DOI:10.1039/c2dt30971h · 4.10 Impact Factor
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    ABSTRACT: The presented work deals with synthesis and isolation of constitutional isomers of triazolo-fused azaphthalocyanines. Distribution of the isomers did not follow the statistical calculations due to steric effects of the substituents preferring the least sterically stressed C(4h) isomer.
    Chemical Communications 03/2012; 48(36):4326-8. DOI:10.1039/c2cc30942d · 6.72 Impact Factor
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    ABSTRACT: Magnesium(II), zinc(II), and metal-free phthalocyanines (Pcs) and azaphthalocyanines (AzaPcs) containing alkylsulfanyl, aryloxy, and dialkylamino peripheral substituents have been synthesized. The complexation of magnesium(II) by metal-free Pcs and AzaPcs has been studied in detail to determine the optimal reaction conditions necessary to ensure a complete conversion. Photophysical and photochemical measurements in tetrahydrofuran showed that magnesium(II) AzaPcs with aryloxy and alkylsulfanyl substituents have excellent fluorescent properties (Φ(F) up to 0.73) and that the corresponding zinc(II) Pcs are efficient singlet oxygen producers (Φ(Δ) up to 0.68). The presence of dialkylamino substituents causes intramolecular charge transfer within the molecule that competes with fluorescence and singlet oxygen formation. Alkylsulfanyl MgAzaPc and ZnAzaPc were the most photostable compounds among the series of studied derivatives. In addition, high molar absorption coefficients (ε ∼ 300,000 M(-1) cm(-1)), absorption (λ(max) ∼ 650 nm), and emission (λ(em) ∼ 660 nm, high Φ(F)) in the red region suggest that these molecules are potential fluorescent probes that are superior to the commercial red cyanine dye Cy5. MgAzaPc, when incorporated into lipidic bilayers of liposomes, maintains excellent fluorescence properties (Φ(F) = 0.64). Water-soluble MgAzaPc with quaternary ammonium peripheral substituents retained a high fluorescence quantum yield even in water (Φ(F) = 0.25). The described properties show that magnesium(II) AzaPcs are excellent red-emitting fluorophores with potential applications as fluorescent probes in sensing or in vitro imaging applications.
    Inorganic Chemistry 03/2012; 51(7):4215-23. DOI:10.1021/ic2027016 · 4.79 Impact Factor
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    ABSTRACT: New unsymmetrical zinc azaphthalocyanines, bearing one substituted aniline as a peripheral substituent, were prepared by using a statistical condensation approach. Both fluorescence and singlet oxygen quantum yields were extremely low in DMF (Φ(F)<0.01, Φ(Δ)<0.02, respectively), but increased after the addition of sulfuric acid, reaching values comparable to controls without aniline substituents (Φ(F)=0.22-0.29, Φ(Δ)=0.40-0.59, respectively). This behavior was attributed to the deactivation of excited states by intramolecular charge transfer from a donor site (aniline), which was blocked after protonation in acidic media. In the protonated form, all of the compounds efficiently emitted light with λ(em) in the region of 662-675 nm. The investigated compounds were anchored to dioleoylphosphatidylcholine (DOPC) unilamellar vesicles and showed response to buffer pH. They were highly fluorescent at low pH values and almost nonfluorescent in neutral solutions. The pK(a) values were determined in DOPC vesicles and ranged between 2.2 and 4.2.
    Chemistry - A European Journal 12/2011; 17(50):14273-82. DOI:10.1002/chem.201101123 · 5.70 Impact Factor

Publication Stats

381 Citations
149.96 Total Impact Points

Institutions

  • 2003–2014
    • Charles University in Prague
      • • Faculty of Pharmacy in Hradec Králové
      • • Department of Pharmaceutical Chemistry and Drug Control (FF Hradec Králové)
      Praha, Praha, Czech Republic
  • 2004
    • University of Hradec Králové
      Königgrätz, Královéhradecký, Czech Republic