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We synthesized new pyrene derivatives with strong bis(para ‐methoxyphenyl)amine donors at the 2,7‐positions and n ‐azaacene acceptors at the K‐region of pyrene. The compounds possess a strong intramolecular charge transfer, leading to unusual properties such as emission in the red to NIR region (700 nm), which has not been reported before for monomeric pyrenes. Detailed photophysical studies reveal very long intrinsic lifetimes of >100 ns for the new compounds, which is typical for 2,7‐substituted pyrenes but not for K‐region substituted pyrenes. The incorporation of strong donors and acceptors leads to very low reduction and oxidation potentials, and spectroelectrochemical studies show that the compounds are on the borderline between localized Robin‐Day class‐II and delocalized Robin‐Day class‐III species.
Efficient quadrupolar chromophores (A–pi–A) with triarylborane moieties as acceptors have been studied by the Marder group regarding their non‐linear optical properties and two‐photon absorption ability for many years. Within the present work, this class of dyes found applications in live‐cell imaging. Therefore, the dyes need to be water‐soluble and water‐stable in diluted aqueous solutions, which was examined in Chapter 2. Furthermore, the influence of the pi‐bridge on absorption and emission maxima, fluorescence quantum yields and especially the two-photon absorption properties of the chromophores was investigated in Chapter 3. In Chapter 4, a different strategy for the design of efficient two‐photon excited fluorescence imaging dyes was explored using dipoles (D–A) and octupoles (DA3). Finding the optimum balance between water‐stability and pi‐conjugation and, therefore, red‐shifted absorption and emission and high fluorescence quantum yields, was investigated in Chapter 5
Post-synthetic shaping of porosity and crystal structure of Ln-Bipy-MOFs by thermal treatment
(2015)
The reaction of anhydrous lanthanide chlorides together with 4,4'-bipyridine yields the MOFs \(^{2}\)\(_{∞}\)[Ln\(_{2}\)Cl\(_{6}\)(bipy)\(_{3}\)]*2bipy, with Ln = Pr-Yb, bipy = 4,4'-bipyridine, and \(^{3}\)\(_{∞}\)[La\(_{2}\)Cl\(_{6}\)(bipy)\(_{5}\)]*4bipy. Post-synthetic thermal treatment in combination with different vacuum conditions was successfully used to shape the porosity of the MOFs. In addition to the MOFs microporosity, a tuneable mesoporosity can be implemented depending on the treatment conditions as a surface morphological modification. Furthermore, thermal treatment without vacuum results in several identifiable crystalline high-temperature phases. Instead of collapse of the frameworks upon heating, further aggregation under release of bipy is observed. \(^{3}\)\(_{∞}\)[LaCl\(_{3}\)(bipy)] and \(^{2}\)\(_{∞}\)[Ln\(_{3}\)Cl\(_{9}\)(bipy)\(_{3}\)], with Ln = La, Pr, Sm, and \(^{1}\)\(_{∞}\)[Ho\(_{2}\)Cl\(_{6}\)(bipy)\(_{2}\)] were identified and characterized, which can also exhibit luminescence. Besides being released upon heating, the linker 4,4'-bipyridine can undergo activation of C-C bonding in ortho-position leading to the in-situ formation of 4,4':2',2 '':4 '',4'''-quaterpyridine (qtpy). qtpy can thereby function as linker itself, as shown for the formation of the network \(^{2}\)\(_{∞}\)[Gd\(_{2}\)Cl\(_{6}\)(qtpy)\(_{2}\)(bipy)\(_{2}\)]*bipy. Altogether, the manuscript elaborates the influence of thermal treatment beyond the usual activation procedures reported for MOFs.