30
T. Maeda
Fig. 2.12 Synthesis of a squaraine-based dye where semi-squaraine skeleton is connected with the
conventional squaraine dye
with squaraine dye can be synthesized by the condensation reaction between dye 8
and indolenium salt.
In the same manner using symmetric squaraine dye with iodine group at both ends,
dye 12 where semi-squaraines are connected at both ends of the squaraine dye can
be obtained (Fig. 2.13). In addition, when a similar reactions are repeated, dye 13 in
which five cyclobutene skeletons are linearly connected can be obtained. Although
the absorption maximum of symmetric squaraine dye as a raw material is observed
at 642 nm, the absorption bands for dyes 9, 12 and 13 were observed at 763 nm,
Fig. 2.13 Synthesis of oligomeric squaraine dye by the Pd-catalyzed cross-coupling reaction
T. Maeda
Fig. 2.12 Synthesis of a squaraine-based dye where semi-squaraine skeleton is connected with the
conventional squaraine dye
with squaraine dye can be synthesized by the condensation reaction between dye 8
and indolenium salt.
In the same manner using symmetric squaraine dye with iodine group at both ends,
dye 12 where semi-squaraines are connected at both ends of the squaraine dye can
be obtained (Fig. 2.13). In addition, when a similar reactions are repeated, dye 13 in
which five cyclobutene skeletons are linearly connected can be obtained. Although
the absorption maximum of symmetric squaraine dye as a raw material is observed
at 642 nm, the absorption bands for dyes 9, 12 and 13 were observed at 763 nm,
Fig. 2.13 Synthesis of oligomeric squaraine dye by the Pd-catalyzed cross-coupling reaction