Synthesis of D–A–A and D–A–D Pyrimidine π-Systems Using Triorganoindium Reagents: Optical, Vibrational, and Electrochemical Studies

Abstract

A series of donor−acceptor−acceptor (D−A− A) and donor−acceptor−donor (D−A−D) systems based on a pyrimidine π-spacer with various substituents at the C-2 position has been successfully prepared. The synthesis involved site-selective palladium cross-coupling reactions of chloropyrimidines with triorganoindium reagents and proceed in good yields and with atom economy. 4-(N,N-Diphenylamino)phenyl was chosen as the donor group and thien-2-yl dicyanovinylene as the acceptor one. The optical, vibrational, electrochemical, and density functional theory (DFT) calculations of these molecular systems were analyzed, and experimental values show the important role of the substituents at the C-2 position of the pyrimidine with stronger electron accepting ability, absorption in a wide range of UV/vis, acceptable fluorescence lifetime, and effective intramolecular charge transfer (ICT) properties. The ICT was observed in both series by the bathochromic shift on increasing the polarity of the solvent. In addition, DFT calculations found lower lowest unoccupied molecular orbitals of D−A−A molecules that suggest good electron ejection and transportation, being good properties for their application in various organic optoelectronic devices.

Preparation of Patterned and Multilayer Thin Films for Organic Electronics via Oxygen‐Tolerant SI‐PET‐RAFT

“…[33] Thep yrimidine-containing PymPTZ was selected for its high quantum yield and rapid rate of reverse intersystem crossing (rISC). [28,[37][38][39][40] Thea mine-functionalized polyaromatic hydrocarbon DPAn exhibits anarrow emission spectrum, high quantum yield, and fast rate of radiative decay. [33,[41][42][43] Thefilms were grown on 100 nm thermal oxide silicon wafers and ITOw ith as heet resistance of 4-10 W/sq (Figure 1).…”

Preparation of Patterned and Multilayer Thin Films for Organic Electronics via Oxygen‐Tolerant SI‐PET‐RAFT

“…As illustrated in Figure 1 a, five acrylic monomers were chosen to represent each of the materials in a multilayer TADF or TAF OLED: a phenylcarbazole CzBA as hole‐transport material, [35] oxadiazole ODA as electron‐transport material, [36] mCzBA as a high triplet level host, [22] PymPTZ as TADF material, [28] and DPAn as an acceptor fluorophore for thermally assisted fluorescence [33] . The pyrimidine‐containing PymPTZ was selected for its high quantum yield and rapid rate of reverse intersystem crossing (rISC) [28, 37–40] . The amine‐functionalized polyaromatic hydrocarbon DPAn exhibits a narrow emission spectrum, high quantum yield, and fast rate of radiative decay [33, 41–43] .…”

Catalytic Synthesis of Luminescent Pyrimidines via Acceptor-less Dehydrogenative Coupling

“…On the whole, the fluorescence quantum yields measured for this series exceed those reported for similarly fluorescent pyrimidines found in the literature. 4,19,33 Comparing a representative sample (P3g) in its solid form and in dichloromethane solution, a stark change from yellow (solid; Figure S2) to colorless (in solution) can be readily discerned by eye, indicating a sensitivity to the surrounding environment that is consistent with charge-transfer character to its excitation. 38 Air-saturated solutions of P1c/P1d/P1g, P2c/P2d/P2g, P3g, and P4d in a variety of solvents were accordingly prepared to investigate the influence of solvent polarity on absorption and emission.…”

“…49 The B3LYP functional has been shown previously to reproduce the solid-state structures of similar pyrimidine compounds. 19 The MN15 functional 50 with 6-311+G(d,p) basis set 49,51 for all atoms were used to accurately estimate the first 50 vertical excitation energies within the time-dependent DFT (TDDFT) formalism, which should be enough to cover the 300-600 nm range of the spectrum. Functionals with large amounts of HF especially in the long range have been proposed to accurately estimate charge transfer transition energies.…”

“…11 As with emissive molecule design in general, there has been expanded interest of late in straightforward and more sustainable preparatory routes to highly substituted, emissive pyrimidines. Moving away from metal-catalyzed cross-coupling methodologies for the derivatization of halogenated pyrimidines, [12][13][14][15][16][17][18][19] for example, would obviate the production of halogenated waste. One-pot, coupling-isomerization sequences 20 and modified Pinner condensations involving silylated amidines 21 have been reported but similarly require functionalized precursors.…”