التفاصيل البيبلوغرافية
| العنوان: |
Ultrafast excited state dynamics of silver ion-mediated cytosine–cytosine base pairs in metallo-DNA. |
| المؤلفون: |
Kohl, Forrest R., Zhang, Yuyuan, Charnay, Aaron P., Martínez-Fernández, Lara, Kohler, Bern |
| المصدر: |
Journal of Chemical Physics; 9/14/2020, Vol. 153 Issue 10, p1-13, 13p |
| مصطلحات موضوعية: |
BASE pairs, SILVER clusters, DNA, SILVER, SILVER ions, SINGLE-stranded DNA, COMPLEX ions, SILVER nitrate |
| مستخلص: |
To better understand the nexus between structure and photophysics in metallo-DNA assemblies, the parallel-stranded duplex formed by the all-cytosine oligonucleotide, dC20, and silver nitrate was studied by circular dichroism (CD), femtosecond transient absorption spectroscopy, and time-dependent-density functional theory calculations. Silver(I) ions mediate Cytosine–Cytosine (CC) base pairs by coordinating to the N3 atoms of two cytosines. Although these silver(I) mediated CC base pairs resemble the proton-mediated CC base pairs found in i-motif DNA at first glance, a comparison of experimental and calculated CD spectra reveals that silver ion-mediated i-motif structures do not form. Instead, the parallel-stranded duplex formed between dC20 and silver ions is proposed to contain consecutive silver-mediated base pairs with high propeller twist-like ones seen in a recent crystal structure of an emissive, DNA-templated silver cluster. Femtosecond transient absorption measurements with broadband probing from the near UV to the near IR reveal an unusually long-lived (>10 ns) excited state in the dC20 silver ion complex that is not seen in dC20 in single-stranded or i-motif forms. This state is also absent in a concentrated solution of cytosine–silver ion complexes that are thought to assemble into planar ribbons or sheets that lack stacked silver(I) mediated CC base pairs. The large propeller twist angle present in metal-mediated base pairs may promote the formation of long-lived charged separated or triplet states in this metallo-DNA. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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