Morphology controlled nanostructures self-assembled from phthalocyanine derivatives bearing alkylthio moieties: effect of sulfur-sulfur and metal-ligand coordination on intermolecular stacking.

To investigate the effect of sulfur-sulfur and metal-ligand coordination on the molecular structure and morphology of self-assembled nanostructures, metal-free 2,3,9,10,16,17,23,24-octakis(isopropylthio)phthalocyanine H(2)Pc(ß-SC(3)H(7))(8) (1) and its copper and lead congeners CuPc(ß-SC(3)H(7))(8) (2) and PbPc(ß-SC(3)H(7))(8) (3) are synthesized and fabricated into organic nanostructures by a phase-transfer method. The self-assembly properties are investigated by electronic absorption and Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Experimental results reveal different molecular packing modes in these aggregates, which in turn result in self-assembled nanostructures with different morphologies ranging from nanobelts for 1 through nanoribbons for 2 to cluster nanoflowers for 3. Intermolecular π-π and sulfur-sulfur interactions between metal-free phthalocyanine 1 lead to the formation of nanobelts. The additional Cu-S coordination bond between the central copper ion of 2 and the sulfur atom of the adjacent molecule of 2 in cooperation with the intermolecular π-π stacking interaction increases the intermolecular interaction, and results in the formation of long nanoribbons for 2. In contrast to compounds 1 and 2, the special molecular structure of complex 3, together with the intermolecular π-π stacking interaction and additional Pb-S coordination bond, induces the formation of Pb-connected pseudo-double-deckers during the self-assembly process, which in turn further self-assemble into cluster nanoflowers. In addition, good semiconducting properties of the nanostructures fabricated from phthalocyanine derivatives 1-3 were also revealed by I-V measurements.

4,5-Bis(isopropyl-sulfan-yl)benzene-1,2-dicarbonitrile.

In the title compound, C(14)H(16)N(2)S(2), the C atoms of the aromatic ring, the two cyanide groups and the two S atoms of the isopropyl-sulfanyl groups are almost coplanar [maximum deviation from the mean plane = 0.042 (7) Å]. In the crystal, inversion dimers linked by aromatic π-π stacking occur, with a centroid-centroid separation of 3.7543 (8) Å.

Helical fibrous nanostructures self-assembled from metal-free phthalocyanine with peripheral chiral menthol units.

(D)- and (L)-enantiomers of a novel metal-free 2(3),9(10),16(17),23(24)-tetrakis(2-isopropyl-5-methylcyclohexoxyl)phthalocyanine (1) with four chiral menthol units attached at the peripheral positions of a phthalocyanine ligand have been synthesized, and characterized. Neither the (D)-1 nor the (L)-1 enantiomer display a circular dichroism (CD) signal in the Soret and Q absorption region of the phthalocyanine ligand, indicating the lack of effective chiral information transfer from the chiral menthol tails to the phthalocyanine chromophore at the molecular level. Their self-assembly properties were systematically studied by CD spectroscopy, transmission electron microscopy, scanning electron microscopy, and atom force microscopy technique. Although four constitutional stereoisomers of each enantiomer were synthesized, because the four chiral menthol substituents are randomly located at peripheral positions of the phthalocyanine ring, cooperation of intermolecular pi-pi interactions between the phthalocyanine rings with chiral discrimination of the chiral side chains of the (D)-1 and the (L)-1 enantiomer induces the formation of one-dimensional helices with left- and right-handed helical molecular arrangement, respectively, according to the CD spectroscopic results. This reveals the effective chiral information transfer from the chiral menthol tails to the phthalocyanine chromophore at the supermolecular level. The formed one-dimensional helices twist around each other to maximize the van der Waals interaction, leading to the formation of highly ordered fibrous nanostructures with both right- and left-handed helicity according to the staggering angles between the neighboring phthalocyanine molecules, indicating the hierarchical formation of these fibrous nanostructures. Careful inspection of these nanofibers indicates the majority of nanofibers with right- and left-handed helicity formed from (D)-1 and (L)-1 enantiomer, respectively, with the ratio of approximately 1.3-1.4:1 among all the fibrous nanostructures obtained. Electronic absorption spectroscopic and X-ray diffraction results reveal the H-aggregate nature of these nanofibers. The present results, showing part of our continuous effort towards preparation of self-assembled nanostructures with helical morphology through molecular design and synthesis, will be helpful on providing new insight into chiral information transfer and expression for synthetic conjugated systems at the supermolecular level.

Sandwich-type mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes with decreased molecular symmetry of Cs: single crystal structure and self-assembled nano-structure.

Two novel sandwich-type mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes with decreased molecular symmetry of Cs M(Pc)[D(NHC(8)H(17))(2)PP] [M = Eu, Lu; Pc = unsubstituted phthalocyaninate; D(NHC(8)H(17))(2)PP = 5,10-di(phenyl)-15,20-di(4-octylamino-phenyl)porphyrinate] (1, 2) have been designed, prepared, and characterized. The single crystal and molecular structure of the Eu analogue has been determined by X-ray diffraction analysis, revealing the head-to-tail supramolecular chains formed from closely bound double-decker molecules depending on the N-H-N hydrogen bonds between one octyl-substituted amidocyanogen group attached at the p-position of meso-attached phenyl group of the porphyrin ligand in the mixed ring double-decker molecule and one aza-nitrogen atom of the phthalocyanine ring in the neighboring double-decker molecule in a zigzag form. Their self-assembled nano-structures have been investigated by transmission electronic microscopy (TEM) and scanning electronic microscopy (SEM). Intermolecular H-N-H hydrogen bonding interaction leads to the formation of nano-structures with fusiform morphology with 220-250 nm average width and about 10 µm length for 1 and 300 nm width and 3-5 µm length for 2, respectively, revealing the effect of molecular size in the direction perpendicular to the tetrapyrrole ring on the dimensions of self-assembled nano-structures.