Glycine: Amino Acid Complexes & Chelates

• Glycine is one of 20 amino acid building blocks of proteins.
• Glycine's structure has an amine group at one end and a carboxylic acid at the other.
• Deprotonation of the acid produces a carboxylate anion, which is the conjugate base of glycine.
• The glycinate anion behaves as a Lewis base and interacts with Lewis acids, including metal centers, forming complexes.
• A "complex" refers to a Lewis acid center interacting with one or more bases, known as "ligands."
• Menkes disease, a rare neurological disorder, is treated with a copper amino acid complex.
• The glycinate anion interacts with the copper ion via a nitrogen and an oxygen center, forming a "chelate" complex.
• The term "chelate" comes from 'claw."
• The geometry of the copper center in chelate complexes is square planar.
• Ligands in these complexes can interact with the two oxygen atoms on the same side (cis configuration) or opposite sides (trans configuration).
• This configurational distinction allows for the formation of two geometric isomers.
• Isomers of bis(glycinato)copper(II) as monohydrate will be synthesized.
• The less thermodynamically stable cis isomer (kinetically stable) transforms into the thermodynamically stable trans isomer using heat (energy).
• Cis-bis(glycinato)copper(II) monohydrate is prepared at relatively low temperatures.
• Trans-bis(glycinato)copper(II) monohydrate preparation requires heat to promote the reactions.
• The reaction solvent, water, will be boiled at reflux.
• Reaction rates generally increase with temperature.
• If the reaction temperature reaches the solvent's boiling point, the solvent evaporates.
• Reflux involves cooling the evaporated solvent with a condenser above the reaction, causing it to drain back into the reaction vessel, preventing solvent loss.
• Boiling chips provide a high surface area for evaporating solvent to form bubbles.
• Without boiling chips, rapid bubble formation can cause the reaction solution to erupt violently.
• A magnetic stirrer is another method to prevent violent eruption from rapid bubbles.
• When working with multiple interconnected glassware pieces, clamp only one piece securely.
• Clamping more than one piece can strain and break the glassware.
• A variac (variable transformer) adjusts the voltage supplied to its outlet.
• Dial marks on the variac indicate the voltage percentage supplied to the outlet.
• Heating mantles behave differently at a given voltage, requiring voltage adjustments to achieve the proper heat.

Explore glycine's role as an amino acid building block and its ability to form complexes. Learn how the glycinate anion acts as a Lewis base, interacting with metal centers like copper to form chelate complexes. Understand the significance of cis and trans configurations in these complexes.