Ken Albrecht 교수

A new synthetic route for carbazole dendrimers was discovered using the copper-catalyzed N-arylation reaction. This synthetic route allowed synthesizing the fourth generation carbazole dendrimer and several derivatives for the first time. The crystal structure, Mark-Houwink-Sakurada plots, and UV-vis and fluorescence studies showed that the dendritic carbazole backbone has a rigid and highly twisted structure. From the measurement of the redox potential of the ferrocene derivatives, the IR spect

A new double layer-type dendrimer with carbazole as the outer layer and phenylazomethine as the inner layer of the dendron was synthesized using the Ullmann reaction and dehydration reaction in the presence of titanium tetrachloride. In this dendrimer, the carbazole units act as excellent hole-transporters, the phenylazomethine units act as metal assembling sites, and the combination of both units provides a thermally stable shell for which the 10% weight loss temperature was over 550 °C. The de

A series of carbazole-dendronized tris(2,4,6-trichlorophenyl)methyl (TTM) radicals have been synthesized. The photophysical properties of dendronized radicals up to the fourth generation were compared systematically to understand how structure-property relationships evolve with generation. The photoluminescence quantum yield (PLQY) was found to increase with the increasing generation, and the fourth generation (G4TTM) in cyclohexane solution showed a PLQY as high as 63 % at a wavelength of 627 n

The synthesis of double-layer-type dendrimers with carbazole and phenylazomethine as the dendron with a symmetric tetraphenylmethane core is reported. Structural modeling studies showed that the G3 dendrimer has a rigid and spherical structure. These dendrimers were thermally stable (Td10% over 500 °C) with the TGA-MS study revealing a degradation mechanism occurring first at the inner-layer phenylazomethine group. The metal (Lewis acid) complexation property of these dendrimers was also studied

A fourth generation carbazole-phenylazomethine dendrimer with a porphyrin core was investigated as a new host for fullerenes (C(60), C(70), and C(84)). This dendrimer has a significantly higher association constant compared to the lower generation dendrimers, and the encapsulation is achieved by the cooperation of the dendron and the core.

Abstract A rational implementation and optimization of thermally activated delayed fluorescent (TADF) dendrimer emitters in light‐emitting electrochemical cells (LECs) sets in the Dendri‐LEC family. They feature outstanding stabilities (90/1050 h for green/yellow devices) that are comparable to the best green/yellow Ir(III)‐complexes (450/500 h) and conjugated polymers (33/5500 h), while offering benefits of low‐cost synthesis and easy upscaling. In particular, a fundamental molecular design tha

The phenylazomethine dendrimer (DPA) has a layer-by-layer electron density gradient that is an analog of the Bohr atom (atom mimicry). In combination with electron pair mimicry, the polymerization of this atom-mimicking dendrimer was achieved. The valency of the mimicked atom was controlled by changing the chemical structure of the dendrimer. By mimicking a divalent atom, a one-dimensional (1D) polymer was obtained, and by using a planar tetravalent atom mimic, a 2D polymer was obtained. These p

A para-substituted phenylazomethine dendrimer (pGnA) coordinates to Lewis acids in a stepwise radial fashion from the inner layer to the outer layer. The inversion of this coordination sequence was achieved for the first time by just changing the substitution position of the phenylazomethine group from the para position to the meta position (mGnA).

Carbazole-benzophenone dendrimers with bulky terminal substituents were synthesized, and the influence of the terminal structure was revealed, i.e. , the terminal structure could suppress concentration quenching and tune the TADF properties.

The effect of axial coordination of pyridine derivatives to the core porphyrin on the fullerene encapsulation of the 4th generation carbazole-phenylazomethine dendrimer (ZnPG2-2) was investigated. The axial coordination of large (bulky) pyridine derivatives affects the cavity in an allosteric manner, and the size-selectivity of the fullerene association could be controlled.

Organic luminescent radicals are a new class of materials with potential applications not only in light-emitting devices but also in the biochemistry field. New tris(2,4,6-trichlorophenyl)methyl (TTM) radicals with alkoxy-substituted carbazole donors were synthesized and characterized. PEG-substituted carbazole-TTM was found to be water-soluble. The water-soluble TTM radical aqueous solution showed fluorescence at 777 nm and the ability to shorten the longitudinal relaxation time (<i>T</i><sub>1

Synthesizing metal clusters with a specific number of atoms on a preparative scale for studying advanced properties is still a challenge. The dendrimer templated method is powerful for synthesizing size or atomicity controlled nanoparticles. However, not all atomicity is accessible with conventional dendrimers. A new tailor-made phenylazomethine dendrimer (DPA) with a limited number of coordination sites (<i>n</i> = 16) and a non-coordinating large poly-phenylene shell was designed to tackle thi

Abstract Tris (2, 4, 6‐trichlorophenyl) methyl (TTM) radical is the most widely studied luminescent radical, and the carbazole‐TTM donor–acceptor (D‐A) dyad is recognized for both high photoluminescence quantum yield and robust photostability. However, despite numerous studies on various D‐A radical dyads, their structure‐property relationship including carbazole‐TTM remains elusive. Here, a series of TTM radical acceptor coupled with methyl‐modified carbazole donor is synthesized and used as a