Versatile Synthesis of Blue Luminescent Siloles and Germoles and Hydrogen‐Bond‐Assisted Color Alteration

Abstract

Group 14 metalloles are an interesting class of Si-, Ge-, or Sn-based annulated p-conjugated molecules.[1] The silole ring system contains a s* orbital on the silicon atom, which effectively interacts with the p* orbital of the butadiene unit, producing a low-lying LUMO. Although a variety of sophisticated silole derivatives have been prepared, the preparation of these well-designed compounds depends heavily on classical Si À C bond-formation methods by using highly reactive organometallic reagents (Scheme 1a). [2,3] This procedure is not always simple, nor is it safe to implement, from the perspective of its applications.Recently, a transition-metal-catalyzed process has been developed to overcome these problems. The groups of Murakami [4] and Shimizu [5] independently reported the pioneering construction of a silole moiety in the presence of a metal catalyst. These protocols were limited by high reaction temperatures and multistep procedures for the preparation of the starting materials. Thus, the development of mild and general methods for the preparation of silole derivatives has remained an important goal. During development of organosilicon compounds containing an aromatic ring, we identified a new methodology based on transition-metal-catalyzed arylation of hydrosilanes with aryl halides.[6] Herein, we report a novel method for constructing the skeletons of Group 14 metalloles from the corresponding dihydrosilanes or dihydrogermanes using Pd-catalyzed E À C (E= Si, Ge) bond formation (Scheme 1b). The effects of the substituents on the physical properties of these materials will be discussed in detail.We examined the cyclic double intramolecular arylation of a 2,2'-diiodobiaryl with a secondary silane in the presence of the base (iPr) 2 EtN, using [Pd(PA C H T U N G T R E N N U N G (tBu) 3 ) 2 ] as the catalyst. [7,8] The results are shown in Scheme 2. The reaction proceeded smoothly to produce the desired dibenzosiloles or -germoles as colorless solids in good to high yields (1-16). The reaction described herein provides a unique method for the preparation of Group 14 metalloles containing a reactive functional group on the aromatic rings, some of which (13-16) are difficult to synthesize when using conventional synthetic methods. 2,2'-Diiodobithiophene gave an inferior yield for product 17; the reduced product was favored. Unfortunately, the intramolecular cyclization of 1-NpPhSiH 2 (Np = naphthyl) or (tBu) 2 SiH 2 with 2,2'-diiodobiphenyl did not occur at all under the present conditions due to the steric crowding of the secondary silanes.The photophysical properties of compounds 1-17 were determined by UV-visible and fluorescence spectroscopies, collected in dichloromethane or in the corresponding crystalline state. These results are summarized in Table 1. The UVvisible absorption spectra showed that the position of the

Unusual Reactivity of Group 14 Hydrides toward Organic Halides: Synthetic Studies and Application to Functional Materials

“…A series of group 14 dibenzometalloes was synthesized from the corresponding dihydrides and 2,2 diiodoarenes using Pd catalyzed bond formation to investigate their photophysical properties (Table 7, 50 61). 24 Compared with the conventional synthetic strategy for preparing dibenzosiloles and dibenzogermoles, the present cyclization has several advantages in terms of functional group tolerances (58 61). Attaching functional groups to the dibenzosilole ring in uences the uorescence quantum yields.…”

A low band gap co-polymer of dithienogermole and 2,1,3-benzothiadiazole by Suzuki polycondensation and its application in transistor and photovoltaic cells

“…17 The resulting molecules demonstrated interesting solid state fluorescence properties. Our synthesis of dithienogermole, and its subsequent polymerisation to afford PGeBTBT is shown in Scheme 1.…”

ARILASI 4-IODIDA ANISOL DENGAN t-BUTIL GERMANIUM MENGGUNAKAN KATALIS PALADIUM

“…Arilasi merupakan salah satu reaksi yang terus dikembangkan hingga saat ini [1]. Salah satu alasan pengembangan reaksi arilasi yakni penggabungan rantai karbon-karbon yang mengandung gugus aril.…”

“…Perbedaan rentang titik leleh yang tidak terlalu besar ini mengindikasikan kemurnian senyawa (1). Untuk selanjutnya dilakukan identifikasi senyawa (1) hasil arilasi 4-iodida anisol dengan t-butil germanium menggunakan GC-MS. Pola fragmentasi massa senyawa (1) disajikan pada Gambar 2.…”

“…Pada spektra 1 H NMR seperti yang tersaji pada Gambar 3 terlihat bahwa adanya empat puncak-puncak proton ekivalen pada senyawa (1). Keempat puncak-puncak proton ekivalen tersebut yakni δ 1,21 ppm (s, 9H), 3,82 ppm (s, 9H), 6,91 ppm (d, 6H, J = 8,3 Hz), 7,42 ppm (d, 6H, J = 8,3 Hz).…”