Lecture 1

Question 1

name the INTERmolecular forces and what role they have.

Answer 1

• lipohilic/LDF/van der wal
• dipole - dipole
• H - bonding

Target binding interactions.

Question 2

name the INTRAmolecular forces and what role they have.

Answer 2

• ionic bonds
  -covalent bonds

drug framework

Question 3

which intermolecular/interatomic interactions are electrostatic?

Answer 3

• ion-ion
• ion-dipole
• dipole-dipole
• cation-pi - anion-pi

Question 4

which intermolecular/interatomic interactions are lipophilic?

Answer 4

• pi-pi stacking
• hydrophobic interactions
• dispersion interactions

Question 5

which intermolecular/interatomic interactions are H-bonding?

Answer 5

-hydrogen bonding
- dipole-dipole only in special cases

Question 6

Explain the bonding properties of aromatic rings.

Answer 6

• usually electron rich = react electrostatically with cations
• electron deficient = react electrostatically with anions.

Question 7

covalent bonds are formed betweeen and…

Answer 7

• non-metals
• more electronegative atom in the bond attracts a larger portion of electron density.
• acquires a partial negative charge

Question 8

role of covalent bond

Answer 8

• strongest instramolecular bonds.
• responsible for physiochemical properties of drug molecules.

Question 9

covalent bonds in drug molecules and biological macromolecules.

Answer 9

• covalent bonds are occassionally formed between them e.g. nucleic acids and enzymes
• responsible for their mutations (non-reversible modification of biological functions)

Question 10

INTERmolecular forces - order of magnitude (KJ mol-1)

Answer 10

lipophilic = <2
dipole - dipole = 1-3
H-bonding = 10-30

Question 11

INTRAmolecular forces - order of magnitude (KJ mol-1)

Answer 11

ionic = 100s*
covalent = 100s

Question 12

ionic interactions are due to?

Answer 12

-attraction between atoms with large differences in electronegativity.
- more electronegative atom abstracts valence electrons from the least electronegative atom = former negatively charged & atom positively charged.

Question 13

what affects ionic interactions

Answer 13

presence of polar solvent molecules

Question 14

lipophilic interactions are due to?

Answer 14

the formation of transient dipoles
generated by motion electrons within covalent bonds

Question 15

lipophilic interaction properties

Answer 15

-weak
-additive
- increase with molar mass

Question 16

what type of interaction between backbone of steric acid molecules and measurement of this?

Answer 16

• lipophilic
• 33.5 KJmol-1

Question 17

when does hydrogen bonding occur

Answer 17

-when H is bonded to an electronegative atom (N or O)
- interacts with an atom with a lone pair of electrons.
- examples - h-bonding between water molecules and nucleobases of nucleic acids.

Question 18

type of interaction vs energy constant proportional.

Answer 18

• ion-ion = 1/r
• ion-dipole = 1/r2
• ion-induced dipole = 1/r3
• dipole-dipole = 1/r4
• dipole-induced dipole = 1/r5
• induced dipole-induced dipole = 1/r6

r = interatomic difference

Question 19

when are electrostatic interactions stronger?

Answer 19

-when there is a strong charge separation.
- charge localisation (due to lack of resonance)

Question 20

when are electrostatic interactions weaker?

Answer 20

-in the presence of partial charges.
- charge delocalisation (due to resonance)