Synthesis and Properties of 4- and 10-Benzoyl-1-azapyrenes

A series of 4- and 10-benzoyl-1-azapyrenes were prepared by a combination of Pd-catalyzed cross-coupling reactions and Brønsted-acid-mediated alkyne-carbonyl-metathesis (ACM). The photophysical and electrochemical properties of the products were studied and compared to theoretical results.

2,7-Diazapyrenes: a brief review on synthetic strategies and application opportunities

2,7-Diazapyrenes are promising azaaromatic scaffolds with a unique structural geometry and supramolecular properties. This core moiety and its derivatives with some N-methyl cations like N-methyl-2,7,-diazapyrenium, and N,N'-dimethyl-2,7-diazapyrenium attract special attention due to their challenging photophysical properties, especially in the context of interactions with DNA and some of its mononucleotides. This review focuses on the analysis of the main synthetic approaches to 2,7-diazapyrene and its functional derivatives employing various strategies under different reaction conditions. The opportunities of applications of 2,7-diazapyrenes, including their remarkable photophysical and supramolecular properties, DNA-bindings, in sensors, molecular electronics, supramolecular systems, and related areas are also highlighted.

Synthesis and Properties of 1-Azapyrenes

A straightforward method for the synthesis of a series of hitherto unknown 1-azapyrenes is reported, which relies on a combination of Pd-catalyzed cross-coupling reactions with Brønsted acid-mediated cycloisomerization reactions. The methodology is highly modular and allows an efficient synthesis of various substituted products in high yields. The structural, electrochemical, and photophysical properties of 1-azapyrenes have been studied by ultraviolet-visible (UV-vis) and fluorescence spectroscopies, cyclic voltammetry, and density functional theory (DFT) calculations.

Generation of Functionalized Alkyl Radicals via the Direct Photoexcitation of 2,2'-(Pyridine-2,6-diyl)diphenol-Based Borates

A new type of alkylborate was developed for the purpose of generating radicals via direct photoexcitation. These borates were prepared using 2,2'-(pyridine-2,6-diyl)diphenol as a tridentate ligand together with organoboronic acids or potassium trifluoroborates. The ready availability of organoboron compounds is a significant advantage of this direct photoexcitation protocol. The excited states of these borates can also serve as strong reductants, enabling various transformations.

2,9-Diazadibenzoperylene and 2,9-Dimethyldibenzoperylene-1,3,8,10-tetratriflates: Key to Functionalized 2,9-Diazaperopyrenes

The synthesis of 2,9-diaza-1,3,8,10-tetratriflato-dibenzoperylene (DDP 3 a) and corresponding 2,9-dimethyl-1,3,8,10-tetratriflato-dibenzoperylene (DBP 3 b) has been developed at multigram scale via reduction of one of the industrially most important high-performance dyes, perylene-3,4,9,10-tetracarboxylic diimide (PTCDI), and of the corresponding dihydroxy peropyrenequinone precursor. The focus of this paper is on the reactivity pattern of 3 a as key intermediate towards highly functionalized 2,9-diazadibenzopyrelenes (DDPs) obtained via catalytic substitution of four triflate by aryl, heteroaryl, alkynyl, aminyl, and O-phosphanyl substituents. The influence of electron-donating substituents (OSiMe₃ , OPt-Bu₂ , N-piperidinyl), electron-withdrawing (OTf, 3,5-bis-trifluoromethyl-phenyl), and of electron-rich π-conjugated (2-thienyl, 4-tert-butylphenyl, trimethylsilyl-ethynyl) substituents on optoelectronic and structural properties of these functionalized DDPs has been investigated via XRD analyses, UV/Vis, PL spectroscopy, and by electroanalytical CV. These results were correlated to results of DFT and TD-DFT calculations. Thus, functionalized DPPs with easily tunable HOMO and LUMO energies and gap became available via a new and reliable synthetic strategy starting from readily available PTCDI.

Reductive O-triflylation of naphthalene diimide: access to alkyne- and amine-functionalized 2,7-diazapyrenes

A reductive one-pot triflylation and silylation of naphthalene diimide is presented. Post-functionalization of the 1,3,6,8-tetratriflato key compound leads to so far non-accessible UHV processable tetraalkynyl and tetraaminyl 2,7-diazapyrenes.