Article
Chemistry, Organic
Issiah B. Lozada, Robert J. Ortiz, Jason D. Braun, J. A. Gareth Williams, David E. Herbert
Summary: A series of intramolecular, donor-stabilized BF2 complexes supported by phenanthridinyl-decorated, beta-ketoiminate chelating ligand scaffolds were characterized by spectroscopy and X-ray diffraction. The orientation of the phenanthridinyl arm in solution is fixed, despite not coordinating to the boron center, and a through-space interaction between phenanthridinyl C-H and a single fluorine atom was observed. Methylation of the phenanthridinyl nitrogen restricts rotation, leading to stronger emission in solution.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Y. A. N. N. I. K. APPIARIUS, A. N. N. E. STAUBITZ
Summary: 1,2-azaborinines, formed by replacing two neighboring carbon atoms in benzene with boron and nitrogen atoms, exhibit increased aromaticity compared to borazine. Experimental analysis of bond lengths, resonance stabilization energies, NMR shifts, and reactivities against electrophiles confirms this. Azaborinines, both monocyclic and polycyclic, have potential applications in materials science, pharmacology, and analytics due to their unique chemical, physical, and optical properties introduced by the polar B-N-unit.
CHEMIE IN UNSERER ZEIT
(2023)
Article
Chemistry, Multidisciplinary
David E. Herbert
Summary: The C-N bond is crucial for the properties and reactivity of coordination complexes. This paper presents an overview of our work investigating the impact of site-selective benzannulation on the chemistry and properties of phenanthridine as a molecule and ligand.
CANADIAN JOURNAL OF CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Dion B. Nemez, Baldeep K. Sidhu, Kevin Carlin, Albert Friesen, David E. Herbert
Summary: The synthesis of novel analogues of the antimalarial (hydroxy)chloroquine was achieved through the substitution of the chloro group at the 4-position of 4,7-dichloroquinolines with amino alcohols. Short-chain and long-chain coupling partners were used, with electron-donating amino and dimethylamino substituents being tolerated. The compounds were characterized using various techniques and crystal structures of selected products were obtained.
CANADIAN JOURNAL OF CHEMISTRY
(2023)
News Item
Chemistry, Multidisciplinary
Robert J. Ortiz, David E. Herbert
Summary: Charge-transfer emission, which is rare for iron coordination complexes, has been observed in an Fe(iii) complex. The emission arises from both metal-to-ligand and ligand-to-metal charge transfer.
Article
Polymer Science
Shuo Li, Katrin Bamberg, Yuzhou Lu, Frank D. Soennichsen, Anne Staubitz
Summary: In this study, linear photoresponsive poly(thioether)s containing diazocine moieties in the polymer backbone were synthesized and their photoisomerization behavior was investigated. The resulting polymers showed reversible photoswitchability between the (Z)- and (E)-configurations. The study highlights the potential use of diazocine as an elongating actuator in macromolecular systems and smart materials.
Article
Chemistry, Inorganic & Nuclear
Robert J. Ortiz, Michael Shepit, Johan van Lierop, J. Krzystek, Joshua Telser, David E. Herbert
Summary: The ligand fields of Ni(II) complexes supported by diarylamido pincer-type amido ligands were investigated. The ligand field parameters were determined using HFEPR, SQUID magnetometry, and electronic absorption spectroscopy. The ability to electrochemically address ligand-based oxidations and the presence of electronic communication between N-amido moieties were also studied.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Biochemistry & Molecular Biology
Issiah B. Lozada, Daniel Gussakovsky, Amarasooriya M. D. S. Jayawardhana, Sean A. Mckenna, Yao-Rong Zheng, David E. Herbert
Summary: This article reports the non-specific interactions between Pt(II) complexes supported by chelating, multidentate ligands and DNA. It is shown that CF3LPtCl exhibits turn-on luminescence through intercalation-mediated mechanism in O2-saturated aqueous buffer. Visible light irradiation significantly enhances its activity, leading to increased photocytotoxicity against a variety of human cancer cell lines. Mechanistic studies reveal improved cellular uptake of CF3LPtCl compared with cisplatin, with localization in the nucleus and mitochondria triggering effective apoptosis. Photosensitization experiments demonstrate that CF3LPtCl efficiently generates singlet dioxygen (1O2), suggesting its potential in photodynamic therapy.
PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
(2023)
Article
Chemistry, Multidisciplinary
Sven Schultzke, Nikolai Scheuring, Pim Puylaert, Matthias Lehmann, Anne Staubitz
Summary: A liquid crystalline polymer is designed to be bendable under visible light, allowing for safer and more efficient use in soft robotics, engineering, and biology.
Article
Chemistry, Inorganic & Nuclear
Yannik Appiarius, Pim Puylaert, Julius Werthschuetz, Tim Neudecker, Anne Staubitz
Summary: The isoelectronic relationship between 1,2-azaborinine and benzene is well known. By deprotonating 1,2-azaborinine, the anionic 1,2-azaboratabenzene is obtained, which has similar properties to pyridine. The study demonstrates the influence of formal boron substitution on the structure and electronic properties.
Article
Chemistry, Multidisciplinary
Melanie Walther, Waldemar Kipke, Raul Renken, Anne Staubitz
Summary: This study presents a novel method for stannylation and borylation of different positions of diazocines, which are azobenzene derived macrocyclic photoswitches with well resolved photostationary states. The results demonstrate their successful use in Stille cross-coupling and Suzuki cross-coupling reactions with organic bromides, achieving high yields.
Article
Chemistry, Multidisciplinary
Ester Maria Di Tommaso, Melanie Walther, Anne Staubitz, Berit Olofsson
Summary: This study developed a synthetic route to access ortho-substituted azobenzenes via novel ortho-substituted azobenzene-functionalized diaryliodonium salts. The selective transfer of the azobenzene moiety to various nucleophiles enables the synthesis of a wide range of ortho-substituted azobenzenes. The photoswitching properties and crystal structure of the reagents were investigated.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Organic
Souvik Ghosh, Christoph Eschen, Nadi Eleya, Anne Staubitz
Summary: This study presents the synthesis and versatile functionalization of 12-membered azobenzene macrocycles (AzMs). By introducing different substituents at different positions in the periphery, the thermal half-lives of the less-stable Z isomers can be significantly influenced. Meta-substitution leads to slower thermal relaxation compared to para-substitution, and electron-withdrawing groups result in slower relaxation than electron-donating groups.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Polymer Science
Ruchira Colaco, Clement Appiah, Anne Staubitz
Summary: In this study, Poly(N-isopropylacrylamide) PNIPAAm hydrogels were modified with a new azobenzene-containing co-monomer to achieve light responsiveness and two phase transitions controlled by light. The lower critical solution transition temperature (LCST) of the hydrogel was reduced by 12 degrees C through the incorporation of 2.5 mol% of the co-monomer. The LCST and structure of the hydrogel can be tuned by the hydrophobicity-hydrophilicity of the (E) and (Z) isomeric state of azobenzene. The large light-driven modulation of the LCST may have diverse applications in the field of soft robotics actuators.
Article
Chemistry, Multidisciplinary
Yannik Appiarius, Sandra Miguez-Lago, Pim Puylaert, Noah Wolf, Sourabh Kumar, Martin Molkenthin, Delia Miguel, Tim Neudecker, Michal Juriek, Araceli G. Campana, Anne Staubitz
Summary: The incorporation of boron-nitrogen units into polycyclic aromatic hydrocarbons improves their optical properties while retaining their geometries. The study found that helicenes with boron-nitrogen groups exhibited higher fluorescence quantum yield and outstanding luminescence dissymmetry, making them suitable candidates for circularly polarized luminescence emitters in materials science.