Article
Macromolecules, Vol. 43, No. 7, 2010 3191
to be 3.2, 21.1, and 9.6° for for M0-C10, M0-C20, and M0-C30,
respectively. These values clearly indicate that the complex
M0-C10 is the most symmetric one, whereas the other two
complexes are significantly more asymmetric, although the
origins of the asymmetry in each case is different. The signifi-
cantly lower oscillator strength for the C-T transition in M0-C30,
when compared with the other two, could be a reflection of the
lower symmetry of the complex, although the relatively close
values of f in the other two cases suggest that other parameters
could also be important in governing the oscillator strength of the
C-T band. These values of f are qualitatively consistent with the
variation of the extinction coefficients of the C-T band seen in
these three cases (Table 1); the extinction coefficients in the cases
of PDI-C1 and PDI-C2 are roughly similar, whereas in the case of
PDI-C3, the C-T absorbance was too low to permit the dilution
experiments; this possibly reflects the significantly lower value of
the extinction coefficient, in addition to the lower Ka value in the
case of PDI-C3.
efforts should enable one to translate the conformational control
achieved in solution to the solid state. Work along these lines are
presently being pursued.
Acknowledgment. We would like to thank the Department of
Atomic Energy for the ORI-Award for the period 2006-2011.
D.K. is indebted to the Indian Institute of Science for providing
the Centenary Postdoctoral Fellowship and is grateful to the
Supercomputer Education and Research Centre (SERC) for
extending computational facilities.
Supporting Information Available: Experimental details of
model monomer synthesis, NMR titrations, EQNMR fitting,
UV-vis titrations, UV-vis dilution experiments, and computa-
tional details, such as absolute energies and optimized Cartesian
coordinates. This material is available free of charge via the
In conclusion, we have developed a simple methodology for
the preparation of a polymer carrying periodically placed elec-
tron-rich aromatic donors (DAN), wherein the spacer segment
linking the units carries a tertiary amine unit. The polymer was
made to fold by the interaction of a small-molecule folding agent
that carries an electron-deficient aromatic acceptor (PDI) and a
carboxylic acid. The formation of a pleated structure is facilitated
References and Notes
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