Synthesis of G0 aminopolyol and aminosugar dendrimers, controlled by NMR and MALDI TOF mass spectrometry

Figures & data

Table 1. The amounts of reactants and solvents used in the synthesis of dendrimers 1–6.

Compound synthesized	Triepoxide (I or II) – amount (mmol)	Aminopolyol (III, IV or V)		CH3OH (solvent) volume (ml)
1	I 3	III 15 mmol	(5 eq)	50
2	I 7	IV 21 mmol	(3 eq)	30
3	I 5	V 15 mmol	(3 eq)	30
4	II 7	III 28 mmol	(4 eq)	50
5	II 7	IV 21 mmol	(3 eq)	30
6	II 4	V 12 mmol	(3 eq)	30

Figure 1. General reaction scheme.

Figure 2. The structure of the substrates I–V, used for the synthesis of dendrimers 1–6 G0 (I and II – triepoxides, III–V – aminopolyols).

Figure 3. Compounds obtained (1–6) and used in MS/MS experiment.

Figure 4. MALDI TOF mass spectrum of: a) a crude compound 1, matrix DHB. Ions: A = [1+H]⁺ i.e. [I+3Tris+H]⁺, m/z 824, B = [I+2Tris+H]⁺, m/z 703; D = [I+DHB+CH₃OH+H]⁺, m/z 647, E =[I+Tris+H₂O+H]^+., m/z 599; b) purified compound 1, c) crude compound 4.

Table 2. Main ions (m/z, % r.a.) in MALDI TOF positive mass spectra of crude products 1–6 and proposed ion structures; APO = aminopolyol.

Ion	Compound	1	2	3	4	5	6
	m/z (% of relative abundance, r.a.)
A (triadduct)	[M+H]^+	824.5	776.4	1046.6	661.3	613.3	883.4
		100%	90%	80%	100%	100%	100%
B (diadduct)	[I+2APO+H]^+ or [II+2APO+H]^+	703.4	671.3	851.5	–	508.4	–
		50%	100%	100%		15%
C (monoadduct + MeOH)	[I+APO+MeOH+H]^+/[II+APO+MeOH+H]^+	–	597.3	687.3	–	434.3	–
			20%	50%		10%
D	[I+2APO-C3H4O+H]^+/[I+DHB+MeOH+H]^+	647.3	–	–	–	–	–
		45%
E (monoadduct + H2O)	[I+APO+H2O+H]^+/[II+APO+H2O+H]^+	599.3	–	–	–	–	–
		20%

Table 3. Chemical shifts of proton (1–6) and carbon (2, 4–6) atoms δ (ppm), obtained from NMR spectra, measured in D₂O; atom labeling given above the table.

Figure 5. ¹H NMR spectrum of compound 4 (D₂O, 298 K).

Figure 6. ¹H-¹³C HSQC NMR spectrum of compound 4 (D₂O, 298 K) in the range 2.4–4.3 ppm (¹H) and 30–180 ppm (¹³C).

Figure 7. Proposed structure of most intense fragment ions in MALDI MSMS spectra of 1–6.

Table 4. Full set of fragment ions, found in MSMS MALDI-QTOF experiment of [M+H]⁺ ions of compounds 1–6.

Ion structure (m/z)
Common for 1 and 4	Specific for 1	Specific for 4
Common for 2 and 5	Specific for 2	Specific for 5
	–
	–
	–
Common for 3 and 6	Specific for 3	Specific for 6

Figure 8. Typical fragmentation for isocyanuric core dendrimers.

Figure 9. Common fragmentation pattern of compounds 1 and 4.

Figure 10. Common fragmentation pattern of compounds 2, 3, 5 and 6 (n=1 or 4).