SFB 663:
Molecular Response to Electronic Excitation
Subject Area
Chemistry
Biology
Term
from 2005 to 2010
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 12901640
The Collaborative Research Centre aims at the comprehensive, mechanistic understanding of photo-induced processes in complex systems that are of relevance in biochemistry, materials science, and medicine. The focus is on reaction cascades proceeding on electronically excited potential energy hypersurfaces. The first objective is to shine light on the underlying mechanisms and to identify and characterise transient states of the reaction paths - in particular long-lived triplet states. Such insights are expected to facilitate, at a later stage, the design of novel or optimised photoactive substances.
Major topics of the Collaborative Research Centre are photostability, photoprotection, and photoreactivity. Photostable compounds are characterised by in-built, efficient mechanisms that protect them against photodegradation. Their response to electronic excitation is fast relaxation to the electronic ground state. In this way, long-lived reactive excited states that could lead to the decomposition of the molecule are populated with low probability. Substances that are not sufficiently photostable by themselves need external protection at light exposure. Photoprotectants quench long-lived, reactive excited states of other molecules by energy transfer mechanisms. On the other hand, one can deliberately make use of electronic excitation to trigger chemical reactions that do not proceed under thermal conditions. Details of the photochemical reaction pathway do not only depend on the photoreceptor itself. Rather, they are influenced by the chemical environment. These effects are particularly pronounced when the chromophore is embedded in heterogeneous environments as found in proteins or polymers.
The photostability of a substance, its reactivity in the electronically excited state, its photoprotective properties as well as the conversion of its photonic excitation to other energy forms are of central importance for many scientific areas. Within the Collaborative Research Centre, these range from photochemical subjects (photolabile caged compounds, photostable dyes) over bio-medical topics (endogenous photoprotectants, photoprotection of chlorophyll during photosynthesis, interaction of DNA bases and aromatic amino acids with UV light) to aspects of material science (photo cross-linkage of membranes, optical force sensors for polymers, bio-mimetic biosensors).
DFG Programme
Collaborative Research Centres
Completed projects
-
A01 - Direkte Spektroskopie von Triplett-, Ladungstransfer- und übergangsverbotenen Singulett-Zuständen in Molekülen und Stoßkomplexen
(Project Head
Weinkauf, Rainer
)
-
A02 - Bestimmung der Lage elektronisch angeregter Zustände, sowie der zugehörigen Strukturen und Lebensdauern
(Project Head
Schmitt, Michael
)
-
A03 - Analyse von Struktur und Reaktivität in elektronisch angeregten Singulett- und Triplettzuständen von Molekülen und Clustern
(Project Head
Gerhards, Markus
)
-
A04 - Primärprozesse und unmittelbare molekulare Folgemechanismen nach Photoanregung in Gas- und kondensierter Phase
(Project Head
Kleinermanns, Karl
)
-
A07 - Elektronische Struktur und Wechselwirkung der Triplettzustände von Carotinoiden und Chlorophyllen
(Project Head
Lubitz, Wolfgang
)
-
A08 - Steigerung der Signalstärke und Photostabilität von Fluorophoren bei der Einzelmolekülspektroskopie
(Project Heads
Müller, Thomas J. J.
;
Seidel, Claus
)
-
B01 - Photoprotektion und Photodynamik durch Mikronährstoffe und analoge Verbindungen
(Project Heads
Martin, Hans Dieter
;
Stahl, Wilhelm
)
-
B01 - Mikronährstoffe und analoge Verbindungen: Photoprotektion und Photostabilität
(Project Heads
Martin, Hans Dieter
;
Stahl, Wilhelm
)
-
B02 - Molekulare Grundlagen photoprotektiver Mechanismen in Pflanzen
(Project Heads
Holzwarth, Alfred R.
;
Jahns, Peter
)
-
B03 - Schwingungsspektroskopische Untersuchungen an Flavin-haltigen biomimetischen Systemen
(Project Heads
Gärtner, Wolfgang
;
Heberle, Joachim
)
-
B04 - Einfluss mechanischer Kräfte auf die photochemischen Primärprozesse polymergebundener Chromophore
(Project Heads
Kühnemuth, Ralf
;
Ritter, Helmut
;
Seidel, Claus
)
-
B05 - Immobilisierung von chromophoren Gruppen an funktionalisierten Copolyimiden
(Project Head
Staudt, Claudia
)
-
B06 - Caged Compounds: Entwicklung verbesserter Werkzeuge für die Biophysik auf der Grundlage eines mechanistischen Verständnisses
(Project Head
Schaper, Klaus
)
-
C01 - Quantenchemische Bestimmung von spinmagnetischen Wechselwirkungen und Singulett-Triplett-Kopplungen mit Multireferenz-Konfigurationswechselwirkungs- Methoden
(Project Head
Marian, Christel M.
)
-
C02 - Dichtefunktional und Hartree-Fock basierte Berechnung der Nullfeldaufspaltung in großen Molekülen
(Project Head
Neese, Frank
)
-
C03 - Energetische Lage von Ladungsübertragungszuständen
(Project Head
Fleig, Timo
)
-
C04 - Elektronisch angeregte Zustände in großen Molekülen
(Project Head
Thiel, Walter
)
-
Z01 - Zentrales Verwaltungsprojekt
(Project Head
Marian, Christel M.
)
