TY  - INPR
A1  - Dietzsch, Julia
A1  - Jayachandran, Ajay
A1  - Mueller, Stefan
A1  - Höbartner, Claudia
A1  - Brixner, Tobias
T1  - Excitonic coupling of RNA-templated merocyanine dimer studied by higher-order transient absorption spectroscopy
T2  - Chemical Communications
N2  - We report the synthesis and spectroscopic analysis of RNA containing the barbituric acid merocyanine rBAM2 as a nucleobase surrogate. Incorporation into RNA strands by solid-phase synthesis leads to fluorescence enhancement compared to the free chromophore. In addition, linear absorption studies show the formation of an excitonically coupled H-type dimer in the hybridized duplex. Ultrafast third- and fifth-order transient absorption spectroscopy of this non-fluorescent dimer suggests immediate (sub-200 fs) exciton transfer and annihilation due to the proximity of the rBAM2 units.
KW  - Barbituric Acid Merocyanines
KW  - Nucleobase Surrogate Incorporation
KW  - Higher-order Transient Absorption Spectroscopy
KW  - rBAM2-labeled RNA strands
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-327772
ET  - submitted version
ER  - 
TY  - JOUR
A1  - Mueller, Stefan
A1  - Lüttig, Julian
A1  - Malý, Pavel
A1  - Ji, Lei
A1  - Han, Jie
A1  - Moos, Michael
A1  - Marder, Todd B.
A1  - Bunz, Uwe H. F.
A1  - Dreuw, Andreas
A1  - Lambert, Christoph
A1  - Brixner, Tobias
T1  - Rapid multiple-quantum three-dimensional fluorescence spectroscopy disentangles quantum pathways
JF  - Nature Communications
N2  - Coherent two-dimensional spectroscopy is a powerful tool for probing ultrafast quantum dynamics in complex systems. Several variants offer different types of information but typically require distinct beam geometries. Here we introduce population-based three-dimensional (3D) electronic spectroscopy and demonstrate the extraction of all fourth- and multiple sixth-order nonlinear signal contributions by employing 125-fold (1⨯5⨯5⨯5) phase cycling of a four-pulse sequence. Utilizing fluorescence detection and shot-to-shot pulse shaping in single-beam geometry, we obtain various 3D spectra of the dianion of TIPS-tetraazapentacene, a fluorophore with limited stability at ambient conditions. From this, we recover previously unknown characteristics of its electronic two-photon state. Rephasing and nonrephasing sixth-order contributions are measured without additional phasing that hampered previous attempts using noncollinear geometries. We systematically resolve all nonlinear signals from the same dataset that can be acquired in 8 min. The approach is generalizable to other incoherent observables such as external photoelectrons, photocurrents, or photoions.
KW  - Atomic and molecular interactions with photons
KW  - Optical spectroscopy
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-202529
VL  - 10
ER  - 
TY  - JOUR
A1  - Stotz, Henrik U.
A1  - Mueller, Stefan
A1  - Zoeller, Maria
A1  - Mueller, Martin J.
A1  - Berger, Susanne
T1  - TGA transcription factors and jasmonate-independent COI1 signalling regulate specific plant responses to reactive oxylipins
JF  - Journal of Experimental Botany
N2  - Jasmonates and phytoprostanes are oxylipins that regulate stress responses and diverse physiological and developmental processes. 12-Oxo-phytodienoic acid (OPDA) and phytoprostanes are structurally related electrophilic cyclopentenones, which activate similar gene expression profiles that are for the most part different from the action of the cyclopentanone jasmonic acid (JA) and its biologically active amino acid conjugates. Whereas JA–isoleucine signals through binding to COI1, the bZIP transcription factors TGA2, TGA5, and TGA6 are involved in regulation of gene expression in response to phytoprostanes. Here root growth inhibition and target gene expression were compared after treatment with JA, OPDA, or phytoprostanes in mutants of the COI1/MYC2 pathway and in different TGA factor mutants. Inhibition of root growth by phytoprostanes was dependent on COI1 but independent of jasmonate biosynthesis. In contrast, phytoprostane-responsive gene expression was strongly dependent on TGA2, TGA5, and TGA6, but not dependent on COI1, MYC2, TGA1, and TGA4. Different mutant and overexpressing lines were used to determine individual contributions of TGA factors to cyclopentenone-responsive gene expression. Whereas OPDA-induced expression of the cytochrome P450 gene CYP81D11 was primarily regulated by TGA2 and TGA5, the glutathione S-transferase gene GST25 and the OPDA reductase gene OPR1 were regulated by TGA5 and TGA6, but less so by TGA2. These results support the model that phytoprostanes and OPDA regulate differently (i) growth responses, which are COI1 dependent but jasmonate independent; and (ii) lipid stress responses, which are strongly dependent on TGA2, TGA5, and TGA6. Identification of molecular components in cyclopentenone signalling provides an insight into novel oxylipin signal transduction pathways.
KW  - lipid signaling
KW  - reactive electrophile oxylipins
KW  - detoxification
KW  - class II TGA factors
KW  - biotic and abiotic stress
KW  - arabidopsis thaliana
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-132318
VL  - 64
IS  - 4
ER  -