Three
distinct types of poly(3-hexylthiophene) (P3HT)-based crystals
were developed using unseeded and seeded protocols. First, unseeded
flat fibrillar and scrolled half-ring-like crystals were prepared
by isothermal crystallization of homo-P3HT and P3HT-b-poly(ethylene glycol) (PEG) block copolymers. Anisotropic accumulation
of grafted coily PEG blocks on the opposite surfaces of P3HT half-rings
having extended backbones reflected scrolling, and their subsequent
crystallization also further intensified this scrolling. The PEGs
assembled into lamellae on both sides of P3HT half-rings with dissimilar
crystalline features, i.e., the outer PEG lamella was thicker (17.4
nm) and wider (23.1 nm) compared to the inner one (15.0 and 18.1 nm).
Furthermore, the crystallinity of PEG coily blocks accumulated on
the P3HT crystals did not change the extended state of P3HT backbones
(17.5 nm) and also the thickness of half-rings (11.0 nm). Second,
with seeding homogeneous P3HT7000-b-PEG5000 solution using homo-PEG5000 tiny crystals,
the cubic PEG single crystals were sandwiched between grafted regioregular
P3HT chains (>99%). The appearance of (020)P3HT and
(100)P3HT spots for tethered P3HTs beside (120)PEG prisms
demonstrated flat-on orderly tethered P3HT backbones on the PEG single
crystalline substrate. Via conjunction between block copolymer and
homopolymer single crystals in channel (PEG)/wire (P3HT-covered PEG)/channel
(PEG) epitaxials, the P3HT rigid brushes were found to be extended
(17.35 nm) on lamellar PEG substrate (6.15 nm). Third, when homogenized
P3HT7000-b-PEG5000 solutions
were seeded by homo-P3HT7000 tiny crystals, the edge-on
orientated fibrillar P3HT single crystals were acquired. Although
the thickness (20–22 nm) and length (60–63 μm)
of P3HT7000-b-PEG5000 fibrillar
single crystals resembled those of homo-P3HT7000 ones,
their backbone lamination in the c axis were significantly
different (2 versus 21); because the P3HT backbones were not capable
of laminating from the coily block sides.
, respectively. The compounds were characterized by elemental analysis, IR and multinuclear NMR ( 1 H, 13 C, 31 P and 119 Sn) spectroscopy. The crystal structures of the complexes were determined by X-ray single crystal analysis, which revealed that complex 1 has a distorted octahedral geometry and complex 2 has a distorted trigonal bipyramidal structure with non-equivalent chlorine atoms. Preliminary antibacterial tests of the compounds against Gram-positive and -negative bacteria were carried out using the filter paper disk method and chloroamphenicol was used as standard for comparison.
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