12.3C Chemisrty and Materials Design Flashcards
Drug
any chemical that measurably alters the physiological function of an organism qualifies as a drug
- Alterations caused by drugs can include activity level, conciousness, coordination, incoming sensory information, mood, or emotion
- Very commonly, drugs inhibit, block, or (less othen) speed up the action of specific enzymes, receptors, or signalling proteins
Medicine
means a drug that is intended to cure a disease or provide symptomatic relief
Drugs from plants
- drug Digoxin is extracted from foxgloves
- painkiller aspirin originated from a compound found in the bark of willow tree
- Taxol an anticancer drug obtained from a bark of a Pacific yew tree
ASPIRIN
made by acylation of salicylic acid
- Aspirin is almost insoluble in water, so its Bioavaliability is limited
- The solubility and bioavaliability of pharmaceutical drugs can be increased by converting them into ionic salts
- Has analgesic, antipyretic, anti-inflammatory, and anti-clotting effect
- Negative side effects include stomach bleeding, allergies, and Reye’s syndrome
Designing new medicinal drugs
Structural features:
- should fit into the active site of essential enzyme of the pathogen and block it
- bind to the active site using its functional groups. The intermolecular bonds formed between drug and target molecule (hydrogen bonding, ionic attraction, dipole-dipole forces)
Designing new medicinal drugs:
Molecular modelling
- Computers judge the fit of potential drug and target molecule
- The interactions between those molecules can be studied before mass production in lab
What are the benefits of molecular modelling?
- lower the number of trials and errors; With molecular modelling, only potentialy successful medicine made and tested.
Chirality in pharmaceutical synthesis
Most of the drugs have optical isomerism. They exist as two enantiomers with identical physical properties, but differemt “pharmaceutical activity” (effect the drug has on the body)
- Thalidomade +enantiomer was used for treatment of morning sickness during pregnancy. -enatiomer caused deformation of limbs of babies. congential deformities.
- Naproxen used to treat the pain of arthritis, other enantiomer can cause liver damage
Ways to prepare pure enantiomers
- Optical resolution for separation a racemic mixture
- Optically active starting materials
- Chiral catalyst
Methods of administration: ORAL
Drug delivered by mouth and absorbed through gastrointestinal tract
Advantages:
+ convenient
+ non-invasive
Disadvantages:
- low % absorption (wasteful and reduces effectiveness)
- drugs may interact with food & beverages
- may be disabled by stomsch acid
- absoption occurs slowly
Methods of administration: PARENTERAL
Drug delivered by injection
Advantages:
+ fast delivery (subcutaneous<intramuscular<intravenous)
+ amounts can be precisely controlled
Disadvantages:
- drug is irretrievable (mistakes cannot be corrected)
- unpleasant & painful (needles or IV lines)
Methods of administration: INHALED
Drug delivered as aerosol into lungs
Advantages:
+ fast delivery, hits brain & body nearly simultaneously
Disadvantages:
- not possible with many drugs
- irretrievable
Methods of administration: RECTAL
Drug delivered by suppository (dissolves in rectum)
Advantages:
+ can be used with nauseted patients
+ avoids problems with stomach acid
Disadvantages:
- distasteful to many people
- can’t take in public
Delivery of drugs: Liposomes
- liposomes made of phospholipids, have hudrophilic head and hydrophobic tails
- reduce drug toxicity in cancer treatment as only get thru walls of tumour’s blood vessels
- used to carry DNA for gene therapy
- deliver the active ingredients of cosmetic agents, such as antiwrinkle creams, deeper into the skin
Delivery of drugs: Gold Nano-Cages
- coated by a polymer PEG;
PEG stops body’s immune system from attacking the gold particles and ejecting them from the bloodstream - used to carry insoluble cancer-fighting drugs to the tumour;
When laser warms the gold atoms, the cage opens, polymer dissolves, releasing the drug
Nanotechnology
is the synthesis and study of compounds, devices and structures within the 10^-9m to 10^−7m (1-100 nanometers) in size.
Allotropes of Carbon:
Buckminsterfullerene C60
- shape of a football ball
- 20 hexagons & 12 pentagons
- Dispersion forces are present
- soft black solid, as it does not require much energy to overcome the weak intermolecular forces
- low sublimation point ~ 600°C
- The carbon atoms joined by delocalised pi bonds, but the delocalisation is reduced by the curvature
- transfer of the current, pi-electrons, from one molecule to the next does NOT occur because of the large band gap
- semiconductor because the extent of electron delocalisation is low
- It is more reactive compared with graphite or diamond, due to the relatively high electron density in certain parts of the molecule.
- It is slightly soluble in solvents such as carbon disulphide and methylbenzene. Neither diamond nor graphite is soluble in common solvents.
USES: - drug delivery (small molecules or atoms can be trapped in the cage of buckminsterfullerene)
Allotropes of Carbon:
Nanotubes
Nanotubes are fullerenes of hexagonally arranged carbon atoms like a single layer of graphite bent into the form of a cylinder
- very high tensile strength
- good electrical conductivity, as some of the electrons are delocalised and are able to move along the cylinder when a voltage is applied.
- relatively high thermal conductivity
- high melting point ~ 3500°C, due to strong covalent bonding throughout the structure
USES: - tiny electrical circuits as ‘wires’;
- electrodes in paper-thin batteries;
- clothing and sports equipment (for added strength);
- treatment of certain types of cancer.
Allotropes of Carbon:
Graphene
Graphene is a single isolated layer of graphite; this hexagonally arranged sheet of carbon atoms is not completely rigid and it can be distorted.
- covalent network solid
- the most chemically reactive form of carbon
- burn at very low temperatures
- extremely strong for its mass
- graphene conducts electricity and heat much better than graphite
USES: - tiny electrical circuits;
- tiny transistors;
- touchscreens,
- solar cells.
Allotropes of Carbon:
Graphene
Graphene is a single isolated layer of graphite; this hexagonally arranged sheet of carbon atoms is not completely rigid and it can be distorted.
- covalent network solid
- the most chemically reactive form of carbon
- burn at very low temperatures
- extremely strong for its mass
- graphene conducts electricity and heat much better than graphite
USES: - tiny electrical circuits;
- tiny transistors;
- touchscreens,
- solar cells.
Problems, implications and issues associated with Nanomaterials
- undiscovered harmful side effects
- new materials should be tested for possible toxicity and carcinogenicity
- health and safety issues
- unexpected catalytic effects
- Self-cleaning windows, sunscreen and modern hard drives are applications that use nanoparticles
CFCs (chlorofluorocarbons)
They were very safe to use because they were so unreactive, which meant they weren’t toxic.
Application:
- coolant in fridges
- aerosols
Ozone (O3)
high in the atmosphere absorbs ultraviolet radiation from the sun, thereby protecting living organisms below from this dangerous radiation.
Ozone and CFCs
chlorine compounds breaking down ozone
CFCl3 + UV-light → CFCl2● + Cl●
Cl● + O3 → ClO● + O2
ClO● + O3 → 2 O2 + Cl●
Overall: 2 O3 → 3 O2
Replacements for CFCs
Hydrofluorocarbons (HFCs):
- Used for fridges and aerosols;
- Break down more quickly because of the presence of hydrogen, so they never reach the ozone layer
HFEs Hydrofluoroethers
- Use as solvents marketed as ‘low global warming’
- used in industry for cleaning and drying
- When fluorine replaces chlorine in a solvent the new compound is more stable, again due to C-F being stronger than C-Cl
