A New Platform of B/N‐Doped Cyclophanes: Access to a π‐Conjugated Block‐Type B₃N₃ Macrocycle with Strong Dipole Moment and Unique Optoelectronic Properties

Abstract

We herein describe a new design principle to achieve B/N-doped cyclophane where an electron-donor block of three triarylamines (Ar 3 N) and an acceptor block of three triarylboranes (Ar 3 B) are spatially separated on opposite sides of the π-extended ring system. DFT computations revealed the distinct electronic structure of the block-type macrocycle MC-b-B3N3 with a greatly enhanced dipole moment and reduced HOMO-LUMO energy gap in comparison to its analogue with alternating B and N sites, MC-alt-B3N3. The unique arrangement of borane acceptor Ar 3 B and amine donor Ar 3 N components in MC-b-B3N3 induces exceptionally strong intramolecular charge transfer in the excited state, which is reflected in a largely red-shifted luminescence at 612 nm in solution.The respective linear open-chain oligomer L-b-B3N3 was also synthesized for comparison. Our new approach to donor-acceptor macrocycles offers important fundamental insights and opens up a new avenue to unique optoelectronic materials.

Expanding new chemistry of aza-boracyclophanes with unique dipolar structures, AIE and redox-active open-shell characteristics

“…6 a , c , e Such a dissymmetry-allowed HOMO–LUMO transition was also the case for the block-type macrocycle M4 with a lower symmetry. 9 Vertical excitations to higher energy states up to S 5 are attributed to a mixed pathway involving the π–π* transition of phenyl linkers and charge transfers from triarylamine moieties ( i.e. endocyclic phenyl or exocyclic aryl) to endocyclic arylborane, and the n–π* transitions from N sites also contribute.…”

“…† Precursor 1 was obtained through the gradual build-up of oligomerization according to previously reported procedures. 9 Starting from the dihalogenated arylamine trimer 1, π-extended pentamers 2 and 3 were prepared by Buchwald–Hartwig coupling with 4-hexylaniline and 4-tetraphenylethenyl amine (TPE-NH 2 ), respectively. Similar reactions in the subsequent C–N cross-couplings yielded the key intermediates 4 and 5.…”

“…Our group and coworkers proposed a new concept of a block-type macrocycle (M4) in which the electron-donor block (N3) and acceptor block (B3) are oriented on opposite sides ( Scheme 1 ), leading to an increased dipole moment ( μ g ) and a reduced HOMO–LUMO energy gap ( E gap ). 9 Computations reveal that the specific patterns of B and N centers as well as the molecular symmetry are closely related to the μ g and E gap levels (Fig. S28 † ), which dramatically impact the respective photophysical and electronic properties.…”

Approaching Dianionic Tetraoxadiborecine Macrocycles: 10‐Membered Bora‐Crown Ethers Incorporating Borafluorenate Units

“…Although the properties of this compound were never explored, this first study led to the realization of other key organoboron macrocycles [8] . Elegant work by Jäkle and co‐workers has highlighted the synthesis and photophysical properties of unusual electron‐deficient bora‐cyclophanes [6i, 9] . In recent years, BF 2 ‐chelated dipyrromethene (BODIPY)‐based macrocycles have garnered significant interest for their broad range of imaging, sensing, and photodynamic properties [10] .…”

A Review of Crystalline Multibridged Cyclophane Cages: Synthesis, Their Conformational Behavior, and Properties

“…Because cyclophane has multiple active sites and a unique cavity structure, it can selectively recognize guest molecules or ions [ 25 , 26 , 27 , 28 , 29 , 30 ]. It also has many properties such as optical properties, catalytic activity and drug activity [ 31 , 32 ], which gives it broad application prospects in the fields of chemical battery [ 33 , 34 ], electrochemical sensor [ 35 ], biomedical, [ 31 ] material science [ 36 ] and so on.…”