COMMUNICATION
First direct-formation and properties of microspherical superstructure.
Morphology of diamineplatinum(II) complexes with isonicotinate{
Hye Ji Yoon,a In Sung Chun,a Young Mee Na,a Young-A Leeb and Ok-Sang Jung*a
Received (in Cambridge, UK) 8th September 2006, Accepted 16th October 2006
First published as an Advance Article on the web 31st October 2006
DOI: 10.1039/b613044e
analysis and IR (n(PF6) = 839 cm21) indicate that the product is
Uniform microspheres (30 mm) of [Pt(en)(iso)(iso?HPF6)] (en =
an adduct of HPF6. Two strong stretching bands at 1709 and
1601 cm21 indicate the coexistence of –COOH and –COO2 in the
product, suggesting that a carboxylate moiety interacts with the
added HPF6. 1H and 13C NMR spectra in D2O show that the ratio
of iso to en is 2 (ESI{). The side-product triethanolamine?HPF6
was isolated and characterized. The microspheres dissolve slowly
in hot water but are insoluble in common organic solvents. The
spherical morphology of the as-synthesized sample was revealed by
SEM (Fig. 1). The diameter of the mature spheres is about 30 mm.
The microspheres consist of about 100 nm needle-like crystals.
X-Ray powder diffraction peaks indicate that the microspheres are
aggregates of small crystals (ESI{). The most striking feature is
that the spherical morphology is rapidly formed. The microspheres
slowly dissolve in an aqueous alkaline solution of 0.05 M
NaHCO3. When the microspheres were left in the solution for
2 days, the shells of the microspheres were isolated from the cores,
as shown in Fig. 2. Such a result indicates that the core/shell
interface is mechanically unstable. Thus, the core is easily removed
from the 7 mm thick shell. The thickness is ascertained from the
difference in size between the sphere in Fig. 1(c) and the sphere in
Fig. 1(d). The N,N-dimethylethylenediamine (dmeda) analogue
was prepared in order to investigate the coligand effects. The
dmeda analogue produced a similar spherical morphology, but
slightly bigger (40–50 mm) spheres. For the dmeda sphere, the unit
ethylenediamine; iso = isonicotinate) has been formed without
intentional addition of any template, that is, a genuine self-
assembly, and their structure, physicochemical properties, and
hydrogenation-catalytic activity have been characterized.
The ability to modulate uniform superstructure/morphology by
means of chemical triggers is of central importance in the recent
development of advanced functional materials.1–5 Unique
morphologies from molecular building blocks promise to provide
size- and shape-dependent materials with task-specific properties
such as photo-electronic devices, pigments, ion exchangers,
dessicants, molecular recognizers, drug delivery systems, biomi-
metics and catalysts.1–9 In particular, facile methods for the
formation of nano-/micro-spherical morphology based on surface
tension, capillary effects, electric and magnetic forces, and
hydrophilic interactions have been highly desired.1,10–14 Various
morphologies of metal chalcogenides have been widely produced,
but the systematic morphogenesis of metal complexes remains
unexplored. In this communication, we present the first direct
formation and related properties of microspherical superstructures
via the reaction of [PtX2(N–N)] (X2 = PF62, ClO42, CF3SO3
2
,
NO32, BF42; N–N = ethylenediamine, N,N-dimethylethylenedi-
amine) with triethanolaminetriisonicotinate (L) in water without
intentional addition of any additive. The microspherical super-
structue can be rapidly constructed via a facile method. To date,
diamineplatinum(II) chemistry has been applied to various fields
such as the isomerism of ambidentate ligands, the synthesis of
antitumor (pro)drugs, the building block of square grids, and the
preparation of luminescent materials via special interaction, and
catalysts.15–18
nanocrystal is a clear parallelepiped crystal (ESI{). The same
reactions of [Pt(en)X2] (X2 = ClO42, CF3SO32, NO32and BF4
2
)
with L were attempted to scrutinize counteranion effects.19,20 For
the various anion analogues, aggregates of small crystals were
formed, but their morphologies were not a uniform spherical
shape. Furthermore, in order to abstract the HPF6 from
[Pt(en)(iso)(iso?HPF6)], addition of extra triethanolamine in the
reaction expectedly gives single crystals of [Pt(en)(iso)2] instead of
the spherical morphology. This fact indicates that the added HPF6
plays an important role in the formation of the microspherical
morphology.
Reaction of [Pt(PF6)2(en)] (en = ethylenediamine) with L in
water, and then evaporation of solvent gave
a uniform
microspherical morphology consisting of [Pt(en)(iso)(iso?HPF6)]
(iso = isonicotinate obtained by the hydrolysis reaction of L){ as
shown in Scheme 1. The microspheres were characterized by
elemental analysis, 1H and 13C NMR, IR, thermal analysis,
contact angle, SEM, and X-ray powder diffraction. Elemental
The multicrystalline aggregates form spontaneously if DG , 0
(free energy of the formation of spherical morphology). The
present molecule owes its properties to the combination of a polar
carboxylate group and a less polar tail moiety. The solubility of the
microspheres provides significant information on the structural
properties. The microspheres are most soluble in a mixture of
water and acetone (1 : 1) rather than pure water or pure acetone,
indicating that the compound has both hydrophilic and hydro-
phobic moieties. The molecules can crystallize in anisotropic unit
nanocrystals. In an aqueous medium, a large number of
nanocrystals consisting of the soap-like molecules congregate in
aDepartment of Chemistry, Pusan National University, Pusan, 609-735,
Korea. E-mail: oksjung@pusan.ac.kr; Fax: (+82)51 516 7421;
Tel: (+82)51 510 2591
bDepartment of Chemistry, Chonbuk National University, Jeonju, 561-
756, Korea. E-mail: ylee@chonbuk.ac.kr; Fax: (+82)63 270 3408;
Tel: (+82) 63 270 3347
{ Electronic supplementary information (ESI) available: 1H, 13C NMR,
IR, thermal analysis, XRD of [Pt(en)(iso)2](HPF6). SEM images of
analogues, water contact angle, structure of [Pt(en)(CH3iso)2](PF6)2, GC
chromatogram and 1H NMR of hydrogenated product. See DOI: 10.1039/
b613044e
492 | Chem. Commun., 2007, 492–494
This journal is ß The Royal Society of Chemistry 2007