Synthesis, characterization and phase behaviors of polypeptides bearing biphenyl mesogens and oligo-ethylene-glycol tails

Abstract

A series of polypeptides bearing biphenyl mesogenic side-chains and oligo-ethylene-glycol (OEG) tails (PPLG n -g-BPOEG m , n = 26 and 63, m = 2, 3, and 7) has been synthesized via a 1,3-dipolar cycloaddition with quantitative grafting density. FTIR results revealed that the polypeptides adopted highly stable -helix in the temperature range of 25200 °C.DSC, POM and WAXS analysis revealed that PPLG n -g-BPOEG m (m ≤ 3) samples with short OEG tail length showed two main phase transitions including crystal to liquid crystalline (smectic C, SmC) phase transition and the melting transition of crystalline E-phase, while PPLG n -g-BPOEG 7 with longer OEG tail length (m = 7) exhibited the melting transitions without the formation of liquid crystalline phase.

Preparation of glycopolypeptides bearing mannose moieties and biphenyl pendants and their upper‐critical‐solution‐temperature‐type thermoresponsive properties in alcohol/water solvent mixtures

“…All polypeptide samples showed characteristic bands at 3280, 2980, 1720, 1654 and 1541 cm −1 , corresponding to v N−H , v C−H , v C=O , amide I and amide II, respectively. The characteristic amide I and amide II bands indicated that all resulting polypeptides adopted an α‐helical conformation in the solid state . PAPLG exhibited v N=N=N at 2092 cm −1 while the polypeptide conjugates (i.e.…”

Synthesis and Properties of Side‐Chain Liquid Crystalline Polypeptides Bearing Various Alkyl Spacers and Oligo‐Ethylene‐Glycol Tails

“…PAPLG 26 , PAHLG 34 , and PAOLG 32 with similar main‐chain lengths were prepared in four steps, including mono‐esterification of l ‐glutamic acid with chloropropyl/hexyl/octyl alcohols, cyclization of γ ‐chloropropyl/hexyl/octyl‐ l ‐glutamates, ring‐opening polymerizations, and nucleophilic substitution in the presence of sodium azide (NaN 3 ). The synthesis and characterization of PPLG 26 ‐BPOEG m ( m = 3 or 7) were reported in our recent publication . The synthetic routes of PHLG 34 ‐BPOEG m and POLG 32 ‐BPOEG m ( m = 3 or 7) were similar to that of PPLG 26 ‐BPOEG m .…”

“…Side‐chain liquid crystalline polypeptides bearing alkyl spacers (i.e., propyl, hexyl, and octyl), biphenyl mesogens, and oligo‐ethylene‐glycol tails (i.e., PPLG‐BPOEG m , PHLG‐BPOEG m , and POLG‐BPOEG m , m = 3 or 7) were synthesized by copper‐mediated alkyne‐azide 1,3‐dipolar cycloaddition between 4′‐prop‐2‐ynyloxy‐biphenyl‐terminated oligo‐ethylene‐glycols (PrBPOEG m , m = 3 or 7) and various poly( γ ‐azidopropyl/hexyl/octyl‐ l ‐glutamate)s (i.e., PAPLG, PAHLG, and PAOLG) (Scheme ). PrBPOEG m samples with different OEG length ( m = 3 or 7) were synthesized via two steps of etherifications from 4,4′‐dihydroxydiphenyl and OEG monomethylether . PAPLG 26 , PAHLG 34 , and PAOLG 32 with similar main‐chain lengths were prepared in four steps, including mono‐esterification of l ‐glutamic acid with chloropropyl/hexyl/octyl alcohols, cyclization of γ ‐chloropropyl/hexyl/octyl‐ l ‐glutamates, ring‐opening polymerizations, and nucleophilic substitution in the presence of sodium azide (NaN 3 ).…”

“…All other chemicals were purchased from Aladdin and used as received. 4′‐Prop‐2‐ynyloxy‐biphenyl‐terminated oligo‐ethylene‐glycols (PrBPOEG m , m = 3 or 7), poly( γ ‐propyl‐ L ‐glutamate)‐ graft ‐(biphenyl‐terminated oligo‐ethylene‐glycols) (PPLG‐BPOEG m , m = 3 or 7), poly( γ ‐6‐azidohexyl‐ L ‐glutamate) (PAHLG), and poly( γ ‐8‐azidooctyl‐ L ‐glutamate) (PAOLG) were synthesized according to reported procedures …”

“…With the development of “clickable” polypeptides [e.g., poly( γ ‐propargyl‐ l ‐ glutamate) (PPLG) and poly(γ‐azidopropyl‐ l ‐glutamate) (PAPLG)], various functional side‐chains (e.g., biomolecules and synthetic polymers) can be readily attached to polypeptide main‐chains with high grafting efficiency . By following this strategy, we have prepared and investigated two series of side‐chain liquid crystalline polypeptides with end‐on biphenyl mesogens, alkyl or oligo‐ethylene‐glycol (OEG) tails, and different main‐chain lengths . The polypeptides showed thermally stable smectic phases depending on the molecular structures.…”