Chemically modified small molecules

1. A method of preparing a monodisperse oligo (ethylene glycol) reagent composition, comprising:

reacting a halo-terminated oligo (ethylene glycol) having (m) monomer subunits and a methoxy end-capping group with a first hydroxyl-terminated oligo (ethylene glycol) having (n) monomer subunits, wherein the first hydroxyl-terminated oligo (ethylene glycol) structure is HO—(CH 2 CH 2 O) n —H, under conditions effective to displace said halo group to thereby form an oligo (ethylene glycol) having (m)+(n) monomer subunits (OEG m+n ), wherein reacting the halo-terminated oligo(ethylene glycol) with the first hydroxyl-terminated oligo (ethylene glycol) comprises adding a 1:1 molar ratio of the halo-terminated oligo(ethylene glycol) to the first hydroxyl-terminated oligo (ethylene glycol) in a solution;

converting the terminal hydroxyl group of OEG m+n into a halo group, —X, to form OEG m+n -X; and

reacting OEG m+n -X with a second hydroxyl-terminated oligo (ethylene glycol) having (n) monomer subunits, wherein the second hydroxyl-terminated oligo structure is HO—(CH 2 CH 2 O) n —H, under conditions effective to displace said halo group to thereby form an oligo(ethylene glycol) having (m)+2(n) monomer subunits (OEG m+2n ), wherein reacting the OEG m+n -X with the second hydroxyl-terminated oligo (ethylene glycol) comprises adding a 1:1 molar ratio of the OEG m+n -X to the second hydroxyl-terminated oligo (ethylene glycol) in a solution;

wherein (m) and (n) each independently range from 1-10, and

wherein (OEG m+2n ) corresponds to the structure CH 3 O(CH 2 CH 2 O) m+2n H, and is present as part of a monodisperse composition of CH 3 O(CH 2 CH 2 O) m+2n H.

2. A method of preparing a monodisperse oligo (ethylene glycol) reagent composition, comprising:

reacting a halo-terminated oligo (ethylene glycol) having (m) monomer subunits and a methoxy end-capping group with a first hydroxyl-terminated oligo (ethylene glycol) having (n) monomer subunits, wherein the first hydroxyl-terminated oligo (ethylene glycol) structure is HO—(CH 2 CH 2 O) n —H, under conditions effective to displace said halo group to thereby form an oligo (ethylene glycol) having (m)+(n) monomer subunits (OEG m+n ), wherein reacting the halo-terminated oligo(ethylene glycol) with the first hydroxyl-terminated oligo (ethylene glycol) comprises adding a 1:1 molar ratio of the halo-terminated oligo(ethylene glycol) to the first hydroxyl-terminated oligo (ethylene glycol) in a solution;

converting the terminal hydroxyl group of OEG m+n into a halo group, —X, to form OEG m+n -X;

reacting OEG m+n -X with a second hydroxyl-terminated oligo (ethylene glycol) having (n) monomer subunits under conditions effective to displace said halo group to thereby form an oligo(ethylene glycol) having (m)+2(n) monomer subunits (OEG m+2n ), wherein OEG m+2n possesses a primary or secondary hydroxyl group, wherein reacting the OEG m+n -X with the second hydroxyl-terminated oligo (ethylene glycol) comprises adding a 1:1 molar ratio of the OEG m+n -X to the second hydroxyl-terminated oligo (ethylene glycol) in a solution;

converting said primary or secondary hydroxyl group into a halo group, —X, to form OEG m+2n -X; and

reacting OEG m+2n -X with a third hydroxyl-terminated oligo (ethylene glycol) having (n) monomer subunits under conditions effective to displace said halo group to thereby form an oligo (ethylene glycol) having m+3n monomer subunits (OEG m+3n ), wherein reacting the OEG m+2n -X with the third hydroxyl-terminated oligo (ethylene glycol) comprises adding a 1:1 molar ratio of the OEG m+2n -X to the third hydroxyl-terminated oligo (ethylene glycol) in a solution;

wherein (m) and (n) each independently range from 1-10; and

wherein (OEG m+3n ) corresponds to the structure CH 3 O(CH 2 CH 2 O) m+3n H, and is present as a monodisperse composition of CH 3 O(CH 2 CH 2 O) m+3n H.

3. The method of claim 1 , wherein (m) ranges from 1-3 and (n) ranges from 2-6.

4. The method of claim 2 , wherein (m) ranges from 1-3 and (n) ranges from 2-6.

5. The method of claim 1 , wherein each reacting step is carried out in the presence of a strong base.

6. The method of claim 2 , wherein each reacting step is carried out in the presence of a strong base.

7. The method of claim 1 , wherein each of the halo groups is Br.

8. The method of claim 2 , wherein each of the halo groups is Br.