B₂N₂‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions

Abstract

A series of polycyclic aromatic hydrocarbons (PAHs), consisting of two pairs of BN units, have been designed and their synthesis has been achieved by electrophilic C−H borylation. Two conjugation extension directions can be found in these B2N2‐embedded PAHs. The B2N2‐containing backbone with shorter effective conjugation length is isoelectronic with diaryl‐fused anthracene, whereas the second derivative, with longer effective conjugation length, is isoelectronic with bis(trans‐arylvinyl)benzene. By incorporating different aryl groups, i.e., furyl, thienyl, benzo[b]furyl, and benzo[b]thienyl groups, into the two crossed directions of the B2N2‐embedded PAHs, their electronic and optical properties have been comparatively investigated by photophysical, electrochemical, and theoretical approaches. It is found that both the substituents and their conjugation extension directions have significant effects on the aromatic and photophysical properties of the B2N2‐embedded PAHs. The conjugation extension in the shorter backbone is more pronounced on the effective conjugation length than the longer backbone. Moreover, all the B2N2‐embedded PAHs behave as both Lewis acids and Lewis bases, and reversible photoluminescence switching can be observed by simply neutralizing the added Lewis acid or Lewis base.

Micellar Suzuki Cross-Coupling between Thiophene and Aniline in Water and under Air

“…2-(2-Thienyl)aniline (3aa). Yellowish solid; mp 35 • C; R f = 0.28; IR (ATR): 3445, 3363, 3101, 3069, 3021 1612, 1488, 1453, 1302, 1245, 1195, 1158, 1142, 1036, 957, 849, 818, 747, 695, 617, 543 cm −1 ; 1 H NMR (400 MHz, CDCl 3 ) δ 7.38 (dd, J = 5.1, 0.7 Hz, 1H), 7.34 (dd, J = 7.6, 1.1 Hz, 1H), 7.27-7.14 (m, 3H), 6.85 (t, J = 7.5 Hz, 1H), 6.80 (d, J = 8.0 Hz, 1H), 4.03 (br, 2H); 13 C NMR (101 MHz, CDCl 3 ) δ 144.1, 141.2, 131.0, 129.1, 127.6, 125.9, 125.3, 120.0, 118.6, 115.9; The spectroscopic data are in accordance to those reported in the literature [25]. 3445,3356,3098,3073,3028,1613,1487,1452,1360,1298,1262,1192,1157,1081,1048,1022,937,896,861,836,786,746,701, 650, 550 cm −1 ; 1 H NMR (400 MHz, CDCl 3 ) δ 7.44 (dd, J = 4.9, 3.0 Hz, 1H), 7.39 (dd, J = 2.8, 1.3 Hz, 1H), 7.29 (dd, J = 4.8, 1.1 Hz, 1H), 7.23 (dd, J = 7.6, 1.5 Hz, 1H), 7.16 (td, J = 7.7, 1.5 Hz, 1H), 6.83 (t, J = 7.5 Hz, 1H), 6.78 (dd, J = 8.0, 0.9 Hz, 1H), 3.85 (br, 2H).…”

“…The reaction of 3-bromoaniuline 1b with 2-thienyl boronic acid 2a was less effective (Table 1, Entry 3); extending the reaction time from 15 to 60 min was enough to increase the yield from 64% to 96% (Table 1, Entry 7). For comparison, we reported in Table 1 (Entries 8-10) classical organic solvent procedures present in the literature carried out with the same class of Pd catalyst, i.e., L 2 PdCl 2 [23,25,30]. The yields were comparable, even if in two cases they were slightly lower, although classic procedures require at least 12 h at higher temperature to complete the transformations and under inert atmosphere.…”

“…1 Isolated yields. 2 Organic solvent procedure with L 2 PdCl 2 catalyst in inert atmosphere reported in [25]. 3 Organic solvent procedure with L 2 PdCl 2 catalyst in inert atmosphere reported in [30].…”

“…Within this context, we were interested in the preparation of thiophene-substituted anilines to be used as precursors for the synthesis of complex heterocyclic systems [19][20][21][22]. Beyond this, thiophene-substituted anilines also serve to produce conductive polymers [23] and as ligand precursors for coordination chemistry [24][25][26]. The obvious strategy for their production involves the cross-coupling processes starting from selected aniline and thiophene precursors, with the Suzuki-Miyaura process being the reaction of choice.…”

BN‐Embedded Polycyclic Aromatic Hydrocarbon Oligomers: Synthesis, Aromaticity, and Reactivity

“…Thes ynthetic approach to BN-embedded PA Hs BN1-BN4 involved ac onstruction of oligoaniline precursors N1-N4 and ended by an electrophilic borylation [14] in the presence of boron bromide and triethylamine (Scheme 1). To prepare the oligomeric precursors,p alladium-catalyzed Buchwald [15] and Suzuki [16] coupling reactions are alternately conducted to construct the oligoaniline backbones.Asshown in Scheme 2, the synthesis of precursors N1 and N2 both started from 2bromoaniline (1), which was directly converted to bis(2bromophenyl)amine (2)a nd 2,5-dibromo-N,N'-bis(2-bromophenyl)benzene-1,4-diamine (3), respectively,v ia Buchwald coupling reaction.…”