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Wojdyla, Michal
Preferred name
Wojdyla, Michal
Official Name
Wojdyla, Michal
Research Output
Now showing 1 - 7 of 7
- PublicationLong-lived excited states in i-motif DNA studied by picosecond time-resolved IR spectroscopy(Royal Society of Chemistry, 2014-03-21)
; ; ; ; ; The transient IR absorption spectrum for UV-excited i-motif DNA is reported for the first time and found to possess complex dynamics pointing to multiple decay processes, including possible charge transfer between packed hemi-protonated C bases.184Scopus© Citations 22 - PublicationUltrafast IR spectroscopy of polymeric cytosine nucleic acids reveal the long-lived species is due to a localised state(RSC Publishing, 2012-02-22)
; ; ; ; ; ; ; ; ; The decay pathways of UV-excited cytosine polymers are investigated using picosecond time-resolved infrared spectroscopy. Similar yields of a non-emissive (1)nÏ * state are found in the single-stranded dC(30) polymer as in the dCMP monomer, but with a longer lifetime in the polymer (80 ps vs. 39 ps). A longer lifetime is also found in the d(CpC) dinucleotide. No evidence of excimer states is observed, suggesting that localised (1)nÏ * excited states are the most significant intermediates present on the picosecond timescale.334Scopus© Citations 11 - PublicationA comparative picosecond transient infrared study of 1-methylcytosine and 5'-dCMP that sheds further light on the excited states of cytosine derivatives(ACS Publications, 2011-03)
; ; ; ; ; ; ; ; ; The role of N1-substitution in controlling the deactivation processes in photoexcited cytosine derivatives has been explored using picosecond time-resolved IR spectroscopy. The simplest N1-substituted derivative, 1-methylcytosine, exhibits relaxation dynamics similar to the cytosine nucleobase and distinct from the biologically relevant nucleotide and nucleoside analogues, which have longer-lived excited-state intermediates. It is suggested that this is the case because the sugar group either facilitates access to the long-lived (1)n(O)Ï * state or retards its crossover to the ground state.419Scopus© Citations 40 - PublicationSynthesis and spectroscopic studies of chiral CdSe quantum dots(RSC Publishing, 2010-08)
; ; ; ; ; Using microwave irradiation, water soluble, optically active, penicillamine (Pen) capped CdSe nanocrystals with broad spectral distribution (430-780 nm) of photoluminescence have been produced and studied by a range of instrumental techniques including absorption, circular dichroism and both steady state and time resolved photoluminescence spectroscopy. The photoluminescence of these nanocrystals is attributed to emission from surface defect states. The decay of the excited state in the nanosecond region, which can be analysed as a triple exponential, depends strongly on the emission wavelength selected, but only weakly on the excitation wavelength.563Scopus© Citations 79 - PublicationEfficient Quenching of TGA-Capped CdTe Quantum Dot Emission by a Surface-Coordinated Europium(III) Cyclen Complex(American Chemical Society, 2013-03-25)
; ; ; ; Extremely efficient quenching of the excited state of aqueous CdTe quantum dots (QDs) by photoinduced electron transfer to a europium cyclen complex is facilitated by surface coordination to the thioglycolic acid capping ligand. The quenching dynamics are elucidated using steady-state emission and picosecond transient absorption.181Scopus© Citations 20 - PublicationExcited state behaviour of substituted dipyridophenazine Cr(III) complexes in the presence of nucleic acids(RSC Publishing, 2010)
; ; ; ; The photophysics and photochemistry of [Cr(phen)2(dppz)]3+ and its 11,12-substituted derivatives [Cr(phen)2(X2dppz)]3+ {X = Me or F} have been studied in the presence of purine nucleotides or DNA using steady state and time-resolved absorption and luminescence spectroscopy. 5'-Adenosine monophosphate (5'-AMP) shows only a weak interaction with the excited states of each complex. By contrast they are efficiently quenched by 5'-guanosine monophosphate (5'-GMP), consistent with photo-induced electron transfer. Laser flash photolysis spectroscopy in the presence of 5'--GMP suggests that both forward and back electron-transfers are rapid. All complexes also display a strong affinity for DNA and evidence for both static and dynamic quenching mechanisms is provided.409Scopus© Citations 13 - PublicationTracking DNA excited states by picosecond-time-resolved infrared spectroscopy: Signature band for a charge-transfer excited state in stacked adenine-thymine systems(American Chemical Society, 2013-07-29)
; ; ; ; UV photoexcitation of an adenine-thymine heterodimer (ApT) in D 2O yields a complex transient infrared signature in the 1500-1600 cm-1 spectral region. The spectral dynamics fit well to a biexponential decay assignable to two transient species. The first, a short-lived species with a lifetime of ca. 5 ps, originates from the vibrationally hot electronic ground state of the unstacked form of the dinucleotide. The second species is longer-lived (ca. 75 ps), and its yield correlates to the amount of stacked dinucleotide present in solution. We assign the longer-lived component to a charge-transfer (A•+pT •-) state by comparison with calculated spectra for the adenine radical cation and thymine radical anion. Significantly, the CT feature is also identified in UV-excited [poly(dA-dT)]2. This experimental observation gives a powerful insight into how base-base interactions lead to extended-lifetime electronic excited states of the nucleic acid bases and how a dimeric structure controls the relaxation pathway. © 2013 American Chemical Society.164Scopus© Citations 69