Synthesis of 5‐Azatetracene and Comparison of Its Optical and Electrochemical Properties with Tetracene

N-Heteroacenes as an Organic Gain Medium for Room-Temperature Masers

The development of future quantum devices such as the maser, i.e., the microwave analog of the laser, could be well-served by the exploration of chemically tunable organic materials. Current iterations of room-temperature organic solid-state masers are composed of an inert host material that is doped with a spin-active molecule. In this work, we systematically modulated the structure of three nitrogen-substituted tetracene derivatives to augment their photoexcited spin dynamics and then evaluated their potential as novel maser gain media by optical, computational, and electronic paramagnetic resonance (EPR) spectroscopy. To facilitate these investigations, we adopted an organic glass former, 1,3,5-tri(1-naphthyl)benzene to act as a universal host. These chemical modifications impacted the rates of intersystem crossing, triplet spin polarization, triplet decay, and spin-lattice relaxation, leading to significant consequences on the conditions required to surpass the maser threshold.

Synthesis and Properties of Diphenylbenzo[j]naphtho[2,1,8-def][2,7]phenanthrolines

A series of hitherto unknown 5,14-diphenylbenzo[j]naphtho[2,1,8-def][2,7]phenanthrolines, containing a 5-azatetracene and a 2-azapyrene subunit, were prepared by combination of Pd-catalyzed cross-coupling reactions with a one-pot Povarov/cycloisomerization reaction. In the final key step four new bonds are formed in one step. The synthetic approach allows for a high degree of diversification of the heterocyclic core structure. The optical and electrochemical properties were studied experimentally and by DFT/TD-DFT and NICS calculations. Due to the presence of the 2-azapyrene subunit, the typical electronic nature and characteristics of the 5-azatetracene moiety are lost and the compounds are electronically and optically more related to 2-azapyrenes.

Novel NBN-Embedded Polymers and Their Application as Fluorescent Probes in Fe3+ and Cr3+ Detection

The isosteric replacement of C═C by B–N units in conjugated organic systems has recently attracted tremendous interest due to its desirable optical, electronic and sensory properties. Compared with BN-, NBN- and BNB-doped polycyclic aromatic hydrocarbons, NBN-embedded polymers are poised to expand the diversity and functionality of olefin polymers, but this new class of materials remain underexplored. Herein, a series of polymers with BNB-doped π-system as a pendant group were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization from NBN-containing vinyl monomers, which was prepared via intermolecular dehydration reaction between boronic acid and diamine moieties in one pot. Poly{2-(4-Vinylphenyl)-2,3-dihydro-1H-naphtho[1,8-de][1,3,2]diazaborinine} (P1), poly{N-(4-(1H-naphtho[1,8-de][1,3,2]diazaborinin-2(3H)-yl)phenyl)acrylamide} (P2) and poly{N-(4-(1H-benzo[d][1,3,2]diazaborol-2(3H)-yl)phenyl)acrylamide} (P3) were successfully synthesized. Their structure, photophysical properties and application in metal ion detection were investigated. Three polymers exhibit obvious solvatochromic fluorescence. As fluorescent sensors for the detection of Fe³⁺ and Cr³⁺, P1 and P2 show excellent selectivity and sensitivity. The limit of detection (LOD) achieved by Fe³⁺ is 7.30 nM, and the LOD achieved by Cr³⁺ is 14.69 nM, which indicates the great potential of these NBN-embedded polymers as metal fluorescence sensors.