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+
acetate, were distilled before use. Dimethyl formamide, aceto-
41 5 2
MS (MALDI-TOF): calc. for [C32H N O ] : m/z 527.33; found:
+
nitrile and dichloromethane were dried over calcium hydride m/z 528.95 [M + H] .
and redistilled under nitrogen prior to use. Tetrahydrofuran L3: (yield 0.23 g, 95%). H NMR (400 MHz, CDCl ): d 7.89–
was dried using sodium benzophenoneketyl and distilled under 7.88 (m, 1H, ArH), 7.48–7.43 (m, 2H, ArH), 7.08 (s, 1H, ArH),
nitrogen immediately before use. 6.43–6.39 (m, 3H, ArH), 6.37 (s, 1H, ArH), 6.28–6.26 (m, 2H,
ArH), 3.32 (q, J ¼ 6.8 Hz, 8H, NCH CH ), 3.28–2.3 (m, 12H,
NCH CH , NCH CH NH and NCH CH NH), 2.04 (s, 4H,
1
3
2
3
4.2 Instrumentation
2
2
2
2
2
2
NCH
NCH
2
2
CH
CH
2
NH and CH
).
2
CH
2
NH
2
) and 1.16 (t, J ¼ 7.2 Hz, 12H,
NMR spectra were recorded on a Varian 400 MHz spectrometer
3
in deuterated chloroform and DMSO-d . MALDI-TOF mass
6
+
MS (MALDI-TOF): calc. for [C H N O ] : m/z 570.37; found:
m/z 572.02 [M + H] .
3
4
46 6 2
spectra were recorded on a Biex Bruker mass spectrometer
using 2-cyano-4-hydroxycinnamic acid or 2,5-dihydroxybenzoic
acid as matrix. UV-Vis absorption spectra were measured on a
Perkin-Elmer Lambda 25 UV-Vis spectrophotometer. Fluores-
cence spectra were recorded using a Perkin-Elmer luminescence
spectrophotometer LS50B. Infrared spectra were obtained on a
Nicolet Impact 410 using KBr pellets. Column chromatography
was conducted using silica gel (Kieselgel 60, 0.063–0.200 mm,
Merck).
+
1
L4: (yield 0.22 g, 87%). H NMR (400 MHz, CDCl ): d 7.82–
3
7
6
.81 (m, 1H, ArH), 7.38–7.36 (m, 2H, ArH), 7.15 (s, 1H, ArH),
.37–6.34 (m, 2H, ArH), 6.30 (s, 2H, ArH), 6.21–6.19 (m, 2H,
ArH), 3.25 (q, J ¼ 6.8 Hz, 8H, NCH
NCH CH NCH CH NH, NCH CH
CH CH NH
) and 1.09 (t, J ¼ 7.2 Hz, 12H, NCH
MS (MALDI-TOF): calc. for [C H N O ] : m/z 613.41; found:
2
CH
NH, NCH
CH
3
), 3.20–2.1 (m, 21H,
CH NH and
).
2
2
,
2
2
2
2
2
2
2
2
2
2
3
+
3
6
51 7 2
+
m/z 615.86 [M + H] .
The morphology and size of the hybrid material before and
1
L5: (yield 0.19 g, 85%). H NMR (400 MHz, CDCl ) d 7.85–7.80
2
+
3
aer adding Hg were observed by transmission electron
microscopy (JEOL, JSM1230) at 20 kV. Prior to examination,
composite samples were immersed in liquid nitrogen 30 min
and then fractured. The specimens were sputter-coated with
gold for enhanced surface conductivity.
(m, 1H, ArH), 7.40 (s, 2H, ArH), 7.05 (s, 1H, ArH), 6.33–6.24 (m,
6H, ArH), 5.27 (bs, 2H, NCH
2
2 2
CH N), 5.06–4.08 (bs, 4H, CH -
CH NH ), 3.28 (bs, 8H, NCH
2
2
2
CH
3
), 3.11 (bs, 2H, NCH
2
2
2
CH
CH
CH
2
2
2
N),
N),
N),
2
2
1
.92–2.86 (m, 2H, NCH
.31–2.29 (m, 2H, NCH
.11 (bs, 12H, NCH CH ).
2
CH
CH
2
2
N), 2.61–2.55 (m, 2H, NCH
N), 2.10–2.02 (m, 2H, NCH
2
2
3
4.3 Synthesis
+
MS (MALDI-TOF): calc. for [C H N O ] : m/z 570.37; found:
.3.1 Rhodamine derivatives. Rhodamine derivatives were m/z 570.94 [M + H] .
3
4
46 6 2
+
4
synthesized by adapting the procedure for similar compounds
4.3.2 Branched poly(L-lactide)maltitol (B-PLLA-M). B-PLLA-
19
reported in the literature. Rhodamine B (0.20 g, 0.42 mmol) M was obtained by direct melt ring-opening polycondensation
was dissolved in 20 mL of ethanol, and ethylenediamine, of L-lactide on the hydroxyl groups of maltitol using a catalytic
diethylenetriamine, triethylenetetra-amine, tetraethylenepenta- amount of Sn(II)2-ethylhexanoate (SnOct2). The poly-
amine or tris(2-aminoethyl)amine (0.22 mL, excess) were added condensation was carried out under vacuum using L-lactide
dropwise to the solution and reuxed overnight (24 h) until the (10.00 g), maltitol (0.1722 g) and SnOct2 (0.0056 g). The mixture
solution lost its red coloration. The solvent was evaporated off of L-lactide and maltitol was placed in a round-bottomed ask
ꢂ
and water (20 mL) added to the residue, and the solution and magnetically stirred in an oil bath at 140 C. The reaction
extracted with methylene chloride (CH
organic phase was combined and washed twice with water, then product was dissolved in chloroform, precipitated using cold
2
Cl
2
; 20 mL ꢀ 2). The was continued for 24 h to obtain a viscous product. The crude
dried over anhydrous Na SO . The solvent was removed by hexane and washed several times with hexane before ltering
2
4
ꢂ
evaporation, and the product dried in vacuo, giving pale yellow and drying in vacuo at 60 C for 48 h to obtain B-PLLA-M.
1
solid compounds L1–L5.
L1: (yield 0.17 g, 84%). H NMR (400 MHz, CDCl
.81 (m, 1H, ArH), 7.45–7.32 (m, 2H, ArH), 7.08–7.03 (m, 1H, PLLA). FT-IR (KBr, cm ): n 3510 and 3823 (O–H stretching),
ArH), 6.42 (s, 1H, ArH), 6.39 (s, 1H, ArH) 6.37 (s, 2H, ArH), 6.38– 2947 and 2997 (C–H stretching), 1745 (C]O ester), 1452 (C–H
H NMR (400 MHz, CDCl
3
): 5.16 (q, –OCH(CH
3
)C(O)– of
)C(O)– of
3
1
): d 7.86– PLLA), 4.18 (d, –CH of maltitol), 1.55 (d, –OCH(CH
3
2
ꢁ1
7
6
6
2
.21 (m, 2H, ArH), 3.32 (q, J ¼ 6.8 Hz, 8H, NCH
2
CH
3
), 3.12 (t, J ¼ bending), 1136 and 1183 (C–O stretching), 756 (CH
2
bending).
.8 Hz, 2H, NCH CH ), 2.23 (t, J ¼ 6.8 Hz, 2H, NCH CH NH ),
2
2
2
2
2
.05 (s, 2H, CH CH NH ) and 1.16 (t, J ¼ 7.2 Hz, 12H,
2
2
2
4.4 Complexation studies of chemosensors with cations
2 3
NCH CH ).
+
MS (MALDI-TOF): calc. for [C30
H
36
N
4
O
2
] : m/z 484.28; found: Studies of selectivity and sensitivity of the complexes of hybrid
+
2+
2+
m/z 485.91 [M + H] .
materials towards cations, such as transition metals (Ni , Co ,
1
2+
2+
2+
+
2+
3+
+
+
+
L2: (yield 0.20 g, 91%). H NMR (400 MHz, CDCl
3
): d 7.90– Cd , Hg , Zn , Ag , Cu , Fe ), alkali metals (Li , Na , K ) and
2
+
2+
7
.88 (m, 1H, ArH), 7.44–7.42 (m, 2H, ArH), 7.09–7.07 (m, 1H, alkaline earths (Ca , Mg ), were carried out by FT-IR, UV, NMR
ArH), 6.43 (s, 1H, ArH), 6.41 (s, 1H, ArH) 6.37 (s, 2H, ArH), 6.28– or uorescence spectroscopy.
6
6
2
.25 (m, 2H, ArH), 3.32 (q, J ¼ 6.8 Hz, 8H, NCH CH ), 3.26 (t, J ¼
The complexation ability of hybrid sensors with cations was
.8 Hz, 2H, NCH CH ), 2.59 (t, J ¼ 6.0 Hz, 2H, NCH CH NH), investigated by spectrophotometric titration in DMSO at 25 C.
2
3
ꢂ
2
2
2
2
.44–2.38 (m, 4H, NCH
2
CH
2
NH), 1.70 (s, 3H, NCH
2
CH
2
NH and 2 mL of the hybrid sensor solution were placed in a spectro-
CH
2
CH NH
2
2
) and 1.16 (t, J ¼ 7.2 Hz, 12H, NCH
2
CH
3
).
photometric cell (1 cm path length). The cation solutions of
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RSC Adv., 2014, 4, 46145–46151 | 46149