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- 저자 : Sastre-Santos, Á (검색결과 6 건)
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C<sub>60</sub> dimers connected through pleiadene bridges: fullerenes talking to each other
Sastre-Santos, Á,ngela,Parejo, Concepció,n,Martí,n-Gomis, Luis,Ohkubo, Kei,Ferná,ndez-Lá,zaro, Fernando,Fukuzumi, Shunichi Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.5
<P>New C<SUB>60</SUB> dimers 1, 2 and 3 that differ in the distance between the two balls, connected through pleiadene bridges have been synthesized. Different synthetic strategies have been used to prepare C<SUB>60</SUB> dimers 1–3. A diastereoisomeric mixture was obtained for C<SUB>60</SUB> dimer 1, which was separated by column chromatography and characterized by NMR. By CV measurements, no interaction between the two balls was found in the ground state in any type of C<SUB>60</SUB> dimer. By reduction with dimeric benzylnicotinamide [(BNA)<SUB>2</SUB>], a two electron reductant, the interaction between both C<SUB>60</SUB> units has been analyzed using electron paramagnetic resonance (EPR). For C<SUB>60</SUB> dimer 3, upon addition of 1 equivalent (BNA)<SUB>2</SUB> no electronic interaction in the C<SUB>60</SUB>˙<SUP>−</SUP>–C<SUB>60</SUB>˙<SUP>−</SUP> was observed due to the long distance between the C<SUB>60</SUB> balls (20 Å). However, for C<SUB>60</SUB> dimer 1, where the distance between radicals is shorter, 10 Å, the electronic interaction in the di(radical anion), C<SUB>60</SUB>˙<SUP>−</SUP>–C<SUB>60</SUB>˙<SUP>−</SUP> in the presence of 1 equivalent of (BNA)<SUB>2</SUB> was observed by EPR, corresponding to a triplet biradical.</P> <P>Graphic Abstract</P><P>Addition of 1 equivalent of (BNA)<SUB>2</SUB> to dimer 1 yields the C<SUB>60</SUB>˙<SUP>−</SUP>–C<SUB>60</SUB>˙<SUP>−</SUP> triplet biradical where electronic interaction is observed. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0jm02635b'> </P>
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El-Khouly, Mohamed E.,Gutié,rrez, Ana M.,Sastre-Santos, Á,ngela,Ferná,ndez-Lá,zaro, Fernando,Fukuzumi, Shunichi The Royal Society of Chemistry 2012 Physical chemistry chemical physics Vol.14 No.10
<P>Photoinduced electron-transfer dynamics of self-assembled donor–acceptor dyads formed by axial coordination of zinc naphthalocyanine, ZnNc, and perylenediimide (PDI) bearing either pyridine (py) or imidazole (im) coordinating ligands were investigated. The PDIim unit was functionalized with <I>tert</I>-octylphenoxy groups at the bay positions, which avoid aggregation providing solubility, to examine the effect of the bulky substituents at the bay positions on the rates of electron-transfer reactions. The combination between zinc naphthalocyanine and perylenediimide entities absorbs light over a wide region of the visible and near infrared (NIR) spectrum. The binding constants of the self-assembled ZnNc:PDIpy (<B>1</B>) and ZnNc:PDIim (<B>2</B>) in toluene were found to be 2.40 × 10<SUP>4</SUP> and 1.10 × 10<SUP>5</SUP> M<SUP>−1</SUP>, respectively, from the steady-state absorption and emission measurements, indicating formation of moderately stable complexes. The geometric and electronic calculations by using an <I>ab initio</I> B3LYP/6-311G method showed the majority of the highest occupied frontier molecular orbital (HOMO) on the zinc naphthalocyanine entity, while the lowest unoccupied molecular orbital (LUMO) was on the perylenediimide entities, suggesting that the charge-separated states of the supramolecular dyads are ZnNc&z.rad;<SUP>+</SUP>:PDI&z.rad;<SUP>−</SUP>. The electrochemical results suggest the exothermic charge-separation process <I>via</I> the singlet states of both ZnNc and PDI entities in nonpolar toluene. Upon coordination of perylenediimide to ZnNc, the main quenching pathway involved charge separation <I>via</I> the singlet-excited states of ZnNc and PDIs. Clear evidence of the intramolecular electron transfer from the singlet-excited state of ZnNc to PDI within the supramolecular dyads in toluene was monitored by the femtosecond laser photolysis by observing the characteristic absorption band of the PDI radical anion (PDI&z.rad;<SUP>−</SUP>) and the ZnNc radical cation (ZnNc&z.rad;<SUP>+</SUP>) in the visible and NIR regions. The rate constants of charge-separation (<I>k</I><SUB>CS</SUB>) processes of the self-assembled dyads <B>1</B> and <B>2</B> were determined to be 4.05 × 10<SUP>10</SUP> and 1.20 × 10<SUP>9</SUP> s<SUP>−1</SUP>, respectively. The rate constant of charge recombination (<I>k</I><SUB>CR</SUB>) and the lifetime of charge-separated states (<I>τ</I><SUB>CS</SUB>) of dyad <B>1</B> were determined to be 2.34 × 10<SUP>8</SUP> s<SUP>−1</SUP> and 4.30 ns, respectively. Interestingly, a slower charge recombination (2.20 × 10<SUP>7</SUP> s<SUP>−1</SUP>) and a longer lifetime of the charge separated state (45 ns) were observed in dyad <B>2</B> in nonpolar toluene by utilizing the nanosecond transient measurements. The absorption in a wide section of the solar spectrum and the high charge-separation/charge-recombination ratio suggest the usefulness of the self-assembled zinc naphthalocyanine–perylenediimide dyads as good photosynthetic models.</P> <P>Graphic Abstract</P><P>Good combination! Efficient electron transfer and relatively long-lived charge-separated states are achieved of light harvesting zinc naphthalocyanine:perylenediimide supramolecular dyads using the femtosecond transient absorption technique in nonpolar toluene. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cp23285e'> </P>
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Rational design of a phthalocyanine–perylenediimide dyad with a long-lived charge-separated state
Blas-Ferrando, Vicente M.,Ortiz, Javier,Bouissane, Latifa,Ohkubo, Kei,Fukuzumi, Shunichi,Ferná,ndez-Lá,zaro, Fernando,Sastre-Santos, Á,ngela The Royal Society of Chemistry 2012 Chemical communications Vol.48 No.50
<P>A new ZnPc–PDI dyad presenting for the first time a charge-separated state lower in energy than the triplet excited state of the ZnPc and PDI has been synthesized. The rational design implies the substitution of the ZnPc with phenoxy groups and the bay substitution of the PDI with sulfonyl substituents. The lifetime of the charge-separated state was 72 μs.</P> <P>Graphic Abstract</P><P>The longest charge-separated state so far, 72 μs, without the addition of external components, for phthalocyanine–perylenediimide arrays has been described. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc31087b'> </P>
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Cé,spedes-Guirao, F. Javier,Ohkubo, Kei,Fukuzumi, Shunichi,Ferná,ndez-Lá,zaro, Fernando,Sastre-Santos, Á,ngela Wiley (John WileySons) 2011 Chemistry, an Asian journal Vol.6 No.11
<P>Two new supramolecular architectures based on zinc phthalocyanine (Pc) and imidazolyl-substituted perylenediimide (PDI), ZnPc/DImPDI/ZnPc 1 and ZnPc/ImPDI 2, have been prepared. A strong electron-donor, ZnPc-8, which contained eight tert-octylphenoxy groups was synthesized to ensure high solubility, thereby reducing aggregation in solution and providing ??-donor features while avoiding regioisomeric mixtures. Also, PDI units were functionalized with tert-octylphenoxy groups at the bay positions, which provide solubility to avoid aggregation in solution, together with one and two imidazole moieties in the amide position, PDI-6 and PDI-4, respectively, to be able to strongly coordinate with the ZnPc complex. Supramolecular complexation studies by (1)H NMR spectroscopy and ESI-MS demonstrate a high coordinative binding constant between imidazole-substituted PDI-4 or PDI-6 and ZnPc-8. The same results were confirmed by UV/Vis and fluorescence titration studies. UV/Vis titration studies revealed the formation of a 1:1 complex ZnPc/ImPDI 2 for the systems ZnPc-8 and PDI-6 and a 2:1 complex ZnPc/DImPDI/ZnPc 1 for the interaction of ZnPc-8 and PDI-4. The binding constant in both cases was determined to be on the order of 10(5) M(-1). Femtosecond laser flash photolysis measurements provided a direct proof of the charge-separated state within both supramolecular assemblies by observing the transient absorption band at 820 nm due to the zinc phthalocyanine radical cation. The lifetimes of charge-separated states are (9.8±3) ns for triad 1 and (3±1) ns for dyad 2. As far as we know, this is the first time that a radical ion pair has been detected in a supramolecular assembled ZnPc-PDI system and has obtained the longest lifetime of a charge-separated state published for ZnPc-PDI assemblies.</P>
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Martí,n-Gomis, Luis,Ohkubo, Kei,Ferná,ndez-Lá,zaro, Fernando,Fukuzumi, Shunichi,Sastre-Santos, Á,ngela Royal Society of Chemistry 2010 Chemical communications Vol.46 No.22
<P>The synthesis and photodynamics in the absence and in the presence of Mg<SUP>2+</SUP> ions of a novel TNF-C<SUB>60</SUB>-SiPc-C<SUB>60</SUB>-TNF pentad are reported. The redox gradient approach allows to obtain a long-lived CS state of 160 ns and 200 μs in the absence and in the presence of Mg<SUP>2+</SUP> ions, respectively.</P> <P>Graphic Abstract</P><P>The redox gradient approach in a TNF-C<SUB>60</SUB>-SiPc-C<SUB>60</SUB>-TNF pentad allows the generation of a long-lived CS state of 160 ns/200 μs in the absence/presence of Mg<SUP>2+</SUP> ions respectively. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c002077j'> </P>
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