Helix-Sense-Selective Polymerization of Phenylacetylenes Having a Porphyrin and a Zinc-Porphyrin Group: One-Handed Helical Arrangement of Porphyrin Pendants

Abstract

: Newly synthesized two kinds of achiral phenylacetylenes having a free-base- or a zinc-porphyrin (1 and Zn1, respectively) were polymerized by using a chiral rhodium catalyst system, Rh+(nbd)[(η6-C6H5)B–(C6H5)3] catalyst and (R)-(+)- or (S)-(–)-1-phenylethylamine ((R)- or (S)-PEA, respectively) cocatalyst. Poly(1) and poly(Zn1) in THF showed a Cotton signal at the absorption region of the porphyrin and the main chain in the circular dichroism (CD) spectra. This result suggests that poly(1) and poly(Zn1) exist in a conformation with an excess of one-handed helix sense and the porphyrin moiety arranged in chiral helical fashion. The one-handed helical structure of poly(1) could be sustained in a mixture of THF/HMPA (10/2, v/v) due to stabilizing by stacking effect of porphyrin moieties along the main chain. This is the first example about helix-sense-selective polymerization by using Rh+(nbd)[(η6-C6H5)B–(C6H5)3] catalyst. Additionally, poly(Zn1) showed about 10 times larger CD intensity in comparison with poly(1). This result suggests the regularity of arrangement of the porphyrin in poly(Zn1) is higher compared with poly(1). Spatial arrangement of porphyrins was achieved by utilizing a one-handed helical poly(phenylacetylenes) as a template.

Syntheses, crystal structures, photo-physical properties, antioxidant and antifungal activities of Mg(II) 4,4′-bipyridine and Mg(II) pyrazine complexes of the 5,10,15,20 tetrakis(4–bromophenyl)porphyrin

“…Spectroscopies, spectrometry and photo-physical measurements 1 H NMR spectra were recorded on a Bruker (Advance 400dpx spectrometer) at 400 MHz. FT -IR spectra were recorded in the region of 400−4000 cm −1 on a Nicolet Impact 410 spectrophotometer.…”

“…The λmax values of these species are listed in Table S4 and compared to several other meso-porphyrins and magnesium metalloporphyrins. The electronic spectra of free base porphyrin contain one intense band around 400 nm (the Soret or B-band) corresponding to strongly allowed transitions to S2 state, followed by four low intensity absorption bands at 515 nm, 549 nm, 590 nm, and 648 nm attributed to Qy (1,0), Qy (0,0), Qx (1,0) and Qx (0,0), respectively (Q-bands). When the metal ion was inserted into the porphyrin ring, the number and intensity of the Q bands were found to decrease [31,35,52], while the intense Soret band showed a red shift up to 7 nm (Fig.…”

“…Porphyrins and their metal complexes were considered as active materials used in polyme rization [1][2][3] and they also exhibited important function as catalysts, in medicinal and pharmaceutical fields [4][5][6], and functional dyes and pigments [7]. For example, iron and manganese porphyrinic complexes were used as efficient catalysts for hydroxylation of alkanes and epoxidation of alkenes [8][9][10][11][12][13][14].…”

Helix-Sense-Selective Polymerization of 3,5-bis(hydroxymethyl)phenylacetylene Rigidly Bearing Galvinoxyl Residues and Their Chiroptical Properties

“…We have already succeeded in the HSSP of various 4-substituted 3,5-bis(hydroxymethyl)phenylacetylenes [6,9,10,11,13,14,15,16]. Then, we explore the HSSP of new achiral monomers rigidly bearing a hydrogalvinoxyl moiety.…”

“…Polymers with helical conformation possess chirality; i.e., the polymers predominantly folding into either a left- or right-handed helical conformation exhibit optical activity despite the absence of asymmetric carbons. Synthesis of helical polymers with a controlled helicity has attracted considerable attention as one of the fundamental factors for their wide variety of potential applications in materials science, such as chiral sensors, chiral catalysts, optical resolution, microelectronic devices, organic magnetic materials, and so on [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17].…”