lecture 1 - bond types in drug molecules

Question 1

WHICH INTERATOMIC/INTERMOLECULAR INTERACTIONS ARE ELECTROSTATIC?

Answer 1

• ion-ion
• ion-dipole
• dipole-dipole
• cation-ion

Question 2

WHICH INTERATOMIC/INTERMOLECULAR INTERACTIONS ARE LIPOPHILIC - (LDF) ?

Answer 2

• pie bond -pie bond stacking interaction
  -hydrophobic interactions
• dispersion interactions

Question 3

WHICH INTERATOMIC/INTERMOLECULAR INTERACTIONS ARE H-BONDING?

Answer 3

• H-H bonding interactions
  (Special case of dipole-dipole)

Question 4

AROMATIC RINGS CLASSIFICATION

Answer 4

• react electrostatically with cations (electron rich)
• react electrostatically with anions (electron deficient)

Question 5

ELECTRONEGAITIVTY IN COVALENT BONDS

Answer 5

• bonds formed between non-metals
• more electronegative atom attracts larger portion of electron density and acquires a partial negative charge.

Question 6

COVALENT BONDS BETWEEN MOLECULES

Answer 6

• the strongest intramolecular bond responsible for physiochemical properties.
• Covalent bonds between drug molecules and biological macromolecules (i.e. nucleic acids and enzymes) are occasionally formed
• they are responsible for non-reversible modification of their biological functions (mutations).

Question 7

WHAT DOES A BOND ENERGY VALUE SHOW?

Answer 7

how strong a bond is and how much energy it releases when broken.

Question 8

ROLE OF INTRAMOLECULAR BONDS (ELECTROSTATIC & LIPOPHILIC)

Answer 8

-hold together structure of drug molecules (drug framework)
- are the interaction between structure of a drug molecule.
- the receptor for the biological target in drug molecules.

Question 9

1kcal/mol

Answer 9

= 4.19KJmol-1

Question 10

INTERMOLECULAR FORCE VS ORDER OF MAGNITUDE

Answer 10

LIPOPHILIC = <2
DIPOLE - DIPOLE = 1-3
H-BONDING = 10-30

Question 11

INTRAMOLECULAR FORCE VS ORDER OF MAGNITUDE

Answer 11

COLAVENT BONDS = 100s
IONIC BONDS = 100s*

Question 12

IONIC INTERACTIONS RESULT FROM…

Answer 12

-the attraction between atoms with large differences in their electronegativity values
-The former becomes negatively charged and the latter positively charged.

Question 13

WHAT WEAKENS IONIC BONDS?

Answer 13

• the presence of polar solvent molecules.
• ionic bonds are strong in the absence of water.
• magnitude decreases from 100s to 10kjmol-1 in water.

Question 14

HOW DO LIPOPHILIC/LDF INTERACTIONS FORM?

Answer 14

due to the transient/temporary dipoles generated by motion of electrons within covalent bonds.

Question 15

LIPOPHILIC PROPERTIES

Answer 15

-intermolecular forces are weak, additive and increase with molar mass.
- longer lipophilic chains = stronger interactions
-lipophilic chain between 2 fatty acids = higher molecular weight.

Question 16

LIPOPHILIC INTERACTION BETWEEN AROMATIC RINGS RESULTS IN?

Answer 16

pie stacking

Question 17

WHEN DOES H-BONDING OCCUR?

Answer 17

-H-bonding occurs when hydrogen is bonded to an electronegative atom (i.e. N or O)
- interacts with an atom with a lone pair of electrons.
-observed in water molecules &nucleic acids/bases

Question 18

WHEN ARE ELECTROSTATIC INTERACTIONS STRONGER?

Answer 18

when there is a strong charge separation.
(weaker when there are partial charges)

Question 19

CHARGE DELOCALISATION DUE TO RESONANCE…

Answer 19

weakens the resulting electrostatic interactions

Question 20

CHARGE LOCALISATION DUE TO LACK OF RESONANCE DELOCALISATION…

Answer 20

results in stronger electrostatic interactions.