5 research outputs found
Photoinduced Energy and Electron-Transfer Reactions by Polypyridine Ruthenium(II) Complexes Containing a Derivatized Perylene Diimide
The
[RuĀ(II) (phen)<sub>2</sub>(pPDIp)]<sup>2+</sup> complex, where
pPDIp is the symmetric bridging ligand phenanthrolineāperyleneāphenanthroline,
shows strong electronic absorption bands attributed to the pPDIp and
{RuĀ(phen)<sub>2</sub>}<sup>2+</sup> moieties in acetonitrile. The
charge-separated intermediate {RuĀ(III) (phen)<sub>2</sub>(pPDIp<sup>āā¢</sup>)} was detected by transient absorption spectroscopy
upon electronic excitation in either the pPDIp or the complex moieties.
The charge-separated intermediate species decays to generate the triplet
state <sup>3</sup>*pPDIp-RuĀ(II) (Ļ<sub>P</sub> = 1.8 Ī¼s)
that sensitizes the formation of singlet molecular oxygen with quantum
yield Ļ<sub>Ī</sub> = 0.57. The dyad in deaerated acetonitrile
solutions is reduced by triethylamine (NEt<sub>3</sub>) to the [RuĀ(II)
(phen)<sub>2</sub>(pPDIp<sup>ā¢ā</sup>)] radical anion
in the dark. The electron-transfer reaction is accelerated by light
absorption. By photolysis of the radical anion, a second electron
transfer reaction occurs to generate the [RuĀ(II) (phen)<sub>2</sub>(pPDIp<sup>2ā</sup>)] dianion. The changes of the color of
solution indicate the redox states of complexes and offer a sensitive
reporter of each stage of redox reaction from start to finish. The
reduced complexes can be converted to the initial complex, using methyl
viologen or molecular oxygen as an electron acceptor. The accumulation
of electrons in two well-separated steps opens promising opportunities
such as in catalysis
Modulation of the Excited States of Ruthenium(II)-perylene Dyad to Access Near-IR Luminescence, Long-Lived Perylene Triplet State and Singlet Oxygen Photosensitization
Herein,
we present a novel ruthenium(II)-perylene dyad (RuPDI-Py)
that combines the photophysical properties of pyrrolidine-substituted
perylene diimide (PDI-Py) and the ruthenium(II) polypyridine complex
[Ru(phen)3]2+. A comprehensive study of excited-state
dynamics was carried out using time-resolved and steady-state methods
in a dimethyl sulfoxide solution. The RuPDI-Py dyad demonstrated excitation
wavelength-dependent photophysical behavior. Upon photoexcitation
above 600 nm, the dyad exclusively exhibits the near-infrared (NIR)
fluorescence of the 1PDI-Py state at 785 nm (Ļfl = 1.50 ns). In contrast, upon photoexcitation between 350
and 450 nm, the dyad also exhibits a photoinduced electron transfer
from the {[Ru(phen)3]2+} moiety to PDI-Py, generating
the charge-separated intermediate state {Ru(III)-(PDI-Py)ā¢ā} (4 Ī¼s). This state subsequently decays to the long-lived
triplet excited state 3PDI-Py (36 Ī¼s), which is able
to sensitize singlet oxygen (1O2). Overall,
tuning 1O2 photoactivation or NIR fluorescence
makes RuPDI-Py a promising candidate for using absorbed light energy
to perform the desired functions in theranostic applications
Luminescent Ruthenium Complexes for Theranostic Applications
The water-soluble
and visible luminescent complexes <i>cis-</i>[RuĀ(L-L)<sub>2</sub>(L)<sub>2</sub>]<sup>2+</sup> where L-L = 2,2-bipyridine
and 1,10-phenanthroline and L= imidazole, 1-methylimidazole, and histamine
have been synthesized and characterized by spectroscopic techniques.
Spectroscopic (circular dichroism, saturation transfer difference
NMR, and diffusion ordered spectroscopy NMR) and isothermal titration
calorimetry studies indicate binding of <i>cis-</i>[RuĀ(phen)<sub>2</sub>(ImH)<sub>2</sub>]<sup>2+</sup> and human serum albumin occurs
via noncovalent interactions with <i>K</i><sub>b</sub> =
9.8 Ć 10<sup>4</sup> mol<sup>ā1</sup> L, Ī<i>H</i> = ā11.5 Ā± 0.1 kcal mol<sup>ā1</sup>, and <i>T</i>Ī<i>S</i> = ā4.46
Ā± 0.3 kcal mol<sup>ā1</sup>. High uptake of the complex
into HCT116 cells was detected by luminescent confocal microscopy.
Cytotoxicity of <i>cis-</i>[RuĀ(phen)<sub>2</sub>(ImH)<sub>2</sub>]<sup>2+</sup> against proliferation of HCT116p53<sup>+/+</sup> and HCT116p53<sup>ā/ā</sup> shows IC<sub>50</sub> values
of 0.1 and 0.7 Ī¼mol L<sup>ā1</sup>. Flow cytometry and
western blot indicate RuphenImH mediates cell cycle arrest in the
G1 phase in both cells and is more prominent in p53<sup>+/+</sup>.
The complex activates proapoptotic PARP in p53<sup>ā/ā</sup>, but not in p53<sup>+/+</sup>. A cytostatic mechanism based on quantification
of the number of cells during the time period of incubation is suggested
Luminescent Ruthenium Complexes for Theranostic Applications
The water-soluble
and visible luminescent complexes <i>cis-</i>[RuĀ(L-L)<sub>2</sub>(L)<sub>2</sub>]<sup>2+</sup> where L-L = 2,2-bipyridine
and 1,10-phenanthroline and L= imidazole, 1-methylimidazole, and histamine
have been synthesized and characterized by spectroscopic techniques.
Spectroscopic (circular dichroism, saturation transfer difference
NMR, and diffusion ordered spectroscopy NMR) and isothermal titration
calorimetry studies indicate binding of <i>cis-</i>[RuĀ(phen)<sub>2</sub>(ImH)<sub>2</sub>]<sup>2+</sup> and human serum albumin occurs
via noncovalent interactions with <i>K</i><sub>b</sub> =
9.8 Ć 10<sup>4</sup> mol<sup>ā1</sup> L, Ī<i>H</i> = ā11.5 Ā± 0.1 kcal mol<sup>ā1</sup>, and <i>T</i>Ī<i>S</i> = ā4.46
Ā± 0.3 kcal mol<sup>ā1</sup>. High uptake of the complex
into HCT116 cells was detected by luminescent confocal microscopy.
Cytotoxicity of <i>cis-</i>[RuĀ(phen)<sub>2</sub>(ImH)<sub>2</sub>]<sup>2+</sup> against proliferation of HCT116p53<sup>+/+</sup> and HCT116p53<sup>ā/ā</sup> shows IC<sub>50</sub> values
of 0.1 and 0.7 Ī¼mol L<sup>ā1</sup>. Flow cytometry and
western blot indicate RuphenImH mediates cell cycle arrest in the
G1 phase in both cells and is more prominent in p53<sup>+/+</sup>.
The complex activates proapoptotic PARP in p53<sup>ā/ā</sup>, but not in p53<sup>+/+</sup>. A cytostatic mechanism based on quantification
of the number of cells during the time period of incubation is suggested
Temperature-Driven Isosymmetric Reversible Phase Transition of the Hormone Estradiol 17Ī² Valerate
The
hormone estradiol 17Ī² valerate (E2V), used in hormone
replacement therapy, undergoes a structural phase transition at 251.1
K on cooling. The crystalline structures of the low and room temperature
phases were determined showing that neither the space group nor the
site symmetry and number of atoms are altered. These phases are related
by a large conformational reorientation of the valerate chain. In
addition, thermal analysis, solid state nuclear magnetic resonance,
and infrared spectroscopy show that the transformation is reversible,
discontinuous, and first order, evidencing the occurrence of an isosymmetric
phase transition, rare for organic compounds