Structural Manipulation of the Conjugated Phenyl Moiety in 3-Phenylbenzofulvene Monomers: Effects on Spontaneous Polymerization

Abstract

Spontaneous polymerization is an intriguing phenomenon in which pure monomers begin their polymerization without initiators or catalysts. Previously, 3-phenylbenzofulvene monomers were found to polymerize spontaneously after solvent removal. Here, eight new 3-substituted benzofulvene monomers 1a-h were synthesized in order to investigate the effects of differently substituted aromatic rings in position 3 of the benzofulvene scaffold on spontaneous polymerization. The newly synthesized monomers maintained the tendency toward spontaneous polymerization. However, monomer 1a, bearing an ortho-methoxy substituted phenyl, polymerized hardly, thus producing low polymerization yields, inhomogeneous structure, and low molecular weight of the obtained polymeric material. This result suggested the importance of the presence of hydrogen atoms in the 2 -position to achieve productive interactions among the monomers in the recognition step preluding the spontaneous polymerization and among the monomeric units in the polybenzofulvene backbones. Moreover, this study paves the way to modify the pendant rings in position 3 of the indene scaffold to synthesize new polybenzofulvene derivatives variously decorated.

Hyaluronan Graft Copolymers Bearing Fatty-Acid Residues as Self-Assembling Nanoparticles for Olanzapine Delivery

“…In particular, an HA-FA-Pg derivative with 2-3 FA residues bearing a propargyl group was successfully used in the covalent coating of inorganic magnetite nanoparticles [12]. Moreover, an HA-FA-Pg derivative bearing 4-5 FA residues was used in the covalent coating of a π-stacked polybenzofulvene derivative [13][14][15][16][17][18][19] to prepare the intriguing organic material TCPB (Figure 1) [20].…”

Densely PEGylated Polybenzofulvene Brushes for Potential Applications in Drug Encapsulation

“…However, the solvent evaporation led to a rapid and exhaustive polymerization of benzofulvene monomer 4,6-PO- BF3k to give the corresponding polymer in the apparent absence of initiators or catalysts. The rapid spontaneous polymerization of this benzofulvene monomer in the complex reaction mixture suggests that the recognition process, which we assumed to be the initial step of the “affinity polymerization” pathway [14,15,27], is capable of operating in a selective and efficient way.…”

“…Indenone 7 [15] was demethylated with BBr 3 to afford compound 8 , which was, in turn, alkylated with propargyl bromide to obtain dipropargyloxy derivative 9 . The structure of this indenone intermediate was confirmed by crystallographic studies (Figure 4).…”

“…To a solution of indenone derivative 7 [15] (0.70 g, 2.07 mmol) in dichloromethane (20 mL) cooled to 0 °C, was added, dropwise, a solution (1 M in dichloromethane) of BBr 3 (16.6 mL, 16.6 mmol), and the reaction mixture was stirred overnight at room temperature. A saturated NaHCO 3 solution was then added until the gas evolution ceased.…”

“…The characterization studies suggested, for this hydrophobic polybenzofulvene derivative, a vinyl structure stabilized by aromatic stacking interactions [9,10]. This intriguing finding led us to explore the chemistry of benzofulvene derivatives [11,12,13,14,15], and to prepare intriguing materials with potential applications in the optoelectronic field [16,17,18,19,20,21,22,23] and pharmaceutical science [24].…”