PMID- 25482308
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20150330
LR  - 20141218
IS  - 2040-3372 (Electronic)
IS  - 2040-3364 (Linking)
VI  - 7
IP  - 3
DP  - 2015 Jan 21
TI  - Synthesis and photophysical properties of new catenated electron donor-acceptor 
      materials with magnesium and free base porphyrins as donors and C60 as the 
      acceptor.
PG  - 1145-60
LID - 10.1039/c4nr06146b [doi]
AB  - A new series of nanoscale electron donor-acceptor systems with [2]catenane 
      architectures has been synthesized, incorporating magnesium porphyrin (MgP) or 
      free base porphyrin (H2P) as electron donor and C60 as electron acceptor, 
      surrounding a central tetrahedral Cu(I)-1,10-phenanthroline (phen) complex. Model 
      catenated compounds incorporating only one or none of these photoactive moieties 
      were also prepared. The synthesis involved the use of Sauvage's metal template 
      protocol in combination with the 1,3-dipolar cycloaddition of azides and alkynes 
      ("click chemistry"), as in other recent reports from our laboratories. Ground 
      state electron interactions between the individual constituents was probed using 
      electrochemistry and UV-vis absorption spectroscopy, while events occurring 
      following photoexcitation in tetrahydrofuran (under both aerobic and anaerobic 
      conditions) at various wavelengths were followed by means of time-resolved 
      transient absorption and emission spectroscopies on the femtosecond and 
      nanosecond time scales, respectively, complemented by measurements of quantum 
      yields for generation of singlet oxygen. From similar studies with model 
      catenates containing one or neither of the chromophores, the events following 
      photoexcitation could be elucidated. The results were compared with those 
      previously reported for analogous catenates based on zinc porphyrin (ZnP). It was 
      determined that a series of energy transfer (EnT) and electron transfer (ET) 
      processes take place in the present catenates, ultimately generating 
      long-distance charge separated (CS) states involving oxidized porphyrin and 
      reduced C60 moieties, with lifetimes ranging from 400 to 1060 nanoseconds. 
      Shorter lived short-distance CS states possessing oxidized copper complexes and 
      reduced C60, with lifetimes ranging from 15 to 60 ns, were formed en route to the 
      long-distance CS states. The dynamics of the ET processes were analyzed in terms 
      of their thermodynamic driving forces. It was clear that intramolecular back ET 
      was occurring in the inverted region of the Marcus parabola correlating rates and 
      driving forces for electron transfer processes. In addition, evidence for triplet 
      excited states as a product of either incomplete ET or back ET was found. The 
      differences in behavior of the three catenates upon photoexcitation are analyzed 
      in terms of the energy levels of the various intermediate states and the driving 
      forces for EnT and ET processes.
FAU - Kirner, Sabrina V
AU  - Kirner SV
AD  - Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular 
      Materials, Friedrich-Alexander-Universitat Erlangen-Nurnberg, D-91058 Erlangen, 
      Germany. dirk.guldi@fau.de.
FAU - Guldi, Dirk M
AU  - Guldi DM
FAU - Megiatto, Jackson D Jr
AU  - Megiatto JD Jr
FAU - Schuster, David I
AU  - Schuster DI
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - England
TA  - Nanoscale
JT  - Nanoscale
JID - 101525249
EDAT- 2014/12/09 06:00
MHDA- 2014/12/09 06:01
CRDT- 2014/12/09 06:00
PHST- 2014/12/09 06:00 [entrez]
PHST- 2014/12/09 06:00 [pubmed]
PHST- 2014/12/09 06:01 [medline]
AID - 10.1039/c4nr06146b [doi]
PST - ppublish
SO  - Nanoscale. 2015 Jan 21;7(3):1145-60. doi: 10.1039/c4nr06146b.