Mof nickel trial

Proposal + Beginner Lab Handout

Ni–Histidine Coordination Framework (Ni–His “Bio-MOF type”)

Goal: Synthesize a real metal–organic coordination network using Ni²⁺ (metal node) and L-histidine (organic linker) from available lab stock.  |  Key control: pH ~ 6.0–6.6 (avoid Ni(OH)₂ precipitation).

1) Why Ni–Histidine? (Project Proposal)

• Real framework: Ni²⁺ coordinates with histidine via carboxylate (–COO⁻) and imidazole-N, giving an extended coordination network (coordination framework / “bio-MOF type”).
• Uses current stock: You already have NiCl₂ (and/or Ni(NO₃)₂·6H₂O) + L-histidine HCl, NaOH, water.
• Nanoscience relevance: Framework morphology + coordination chemistry + adsorption/ion binding + potential catalytic relevance of Ni.
• Easy proof: XRD (new crystalline pattern), FTIR (coordination shifts), SEM (crystals), and a quick dye uptake test (methylene blue if desired).

2) Safety (Mandatory)

• Wear lab coat, gloves, and goggles.
• Ni salts are irritants/toxic—avoid inhalation/skin contact; handle carefully.
• NaOH is corrosive—add slowly; rinse spills immediately with water.
• Autoclave: fill ≤80%, cool naturally, never open hot/pressurized.

3) Chemicals & Equipment

Chemicals

• Nickel(II) chloride (NiCl₂) OR Nickel(II) nitrate hexahydrate (Ni(NO₃)₂·6H₂O)
• L-Histidine hydrochloride (check bottle: HCl or HCl·H₂O)
• NaOH pellets/flakes (to prepare 0.1 M NaOH)
• DI water
• 2-propanol (washing; recommended)
• pH paper

Equipment

• Electronic balance (4-digit)
• 2 × 250 mL beakers, stirrer + stir bar
• Measuring cylinder
• Funnel + filter paper (or centrifuge)
• Teflon-lined autoclave + hot air oven (60 °C)

4) Batch Plan for ≥ 4 g Total Product

Run two identical batches at 10 mmol scale and combine after drying: Batch-1 (10 mmol) + Batch-2 (10 mmol) → target total ≥ 4 g. If yield is low, run Batch-3 and combine.

5) Quantities (Per Batch = 10 mmol)

Important: You must choose ONE nickel salt route below. If you are unsure which Ni salt you have, read the bottle label.

Important: For histidine, if bottle says L-histidine HCl use 1.916 g; if it says L-histidine HCl·H₂O use 2.096 g.

Option A (Preferred if available): NiCl₂ Route

Item	Quantity (10 mmol)	Notes
NiCl2	1.297 g	Nickel source (10 mmol)
L-Histidine HCl	1.916 g	If bottle says L-histidine HCl
L-Histidine HCl·H2O	2.096 g	If bottle says monohydrate
DI water	80 mL total	40 mL Ni solution + 40 mL histidine solution

Option B (Very common stock): Ni(NO₃)₂·6H₂O Route

Item	Quantity (10 mmol)	Notes
Ni(NO3)2·6H2O	2.909 g	Nickel nitrate hexahydrate (10 mmol)
L-Histidine HCl	1.916 g	If bottle says L-histidine HCl
L-Histidine HCl·H2O	2.096 g	If bottle says monohydrate
DI water	80 mL total	40 mL Ni solution + 40 mL histidine solution

6) Prepare 0.1 M NaOH (One-time; use for both batches)

1. Weigh 0.40 g NaOH.
2. Dissolve in ~70 mL DI water.
3. Make final volume to 100 mL with DI water.
4. Label: “0.1 M NaOH, date, prepared by”.

Why dilute? Beginner-friendly pH control to prevent Ni(OH)₂ formation.

7) Step-by-Step Procedure (Batch-1)

Step 1 — Prepare Nickel solution

1. Take a clean 250 mL beaker.
2. Add 40 mL DI water.
3. Add Ni salt (choose Option A or B mass above).
4. Stir until fully dissolved (clear green solution may appear).

Step 2 — Prepare Histidine solution

1. Take another clean 250 mL beaker.
2. Add 40 mL DI water.
3. Add histidine mass: 1.916 g (HCl) or 2.096 g (HCl·H₂O).
4. Stir until dissolved.

Step 3 — Mix

1. Under stirring, add histidine solution slowly into the nickel solution.
2. Stir for 10 minutes.

Step 4 — pH Adjustment (CRITICAL)

1. Measure pH with pH paper.
2. Add 0.1 M NaOH dropwise (1–2 drops at a time) under stirring.
3. Stop at pH 6.0–6.6 (ideal ~ 6.3).

Correct observation: solution remains clear or slightly turbid.

Wrong observation: immediate thick green precipitate → Ni(OH)₂ formed (pH too high).
Fix: restart and add NaOH slower; do not exceed pH 6.6.

Step 5 — Hydrothermal Framework Growth

1. Transfer mixture to Teflon liner.
2. Fill ≤ 80%.
3. Seal and heat at 120 °C for 12 hours.
4. Allow to cool naturally to room temperature.

Step 6 — Collect, wash, dry

1. Collect solid by filtration (or centrifuge).
2. Wash with DI water: 3 × 20 mL.
3. Wash with 2-propanol: 2 × 20 mL (recommended).
4. Dry at 60 °C for 6–8 hours.
5. Weigh and record mass (yield).

8) Batch-2 (Repeat Identically)

Repeat the same steps and combine dried Batch-1 + Batch-2 to reach ≥ 4 g total.

9) How to Confirm You Made a Framework (Not Ni(OH)₂)

• Powder XRD (main proof): new crystalline pattern; should not match Ni(OH)₂ or NiO patterns.
• FTIR: shifts in carboxylate and imidazole bands vs free histidine.
• SEM: crystal-like morphology (plates/blocks/needles depending on conditions).
• Optional dye test: Methylene blue adsorption: 10 mg material + 10 mL dye, shake 1 h; compare to blank.

10) Troubleshooting

Problem	Likely cause	Fix
Instant green precipitate before autoclave	pH too high → Ni(OH)2	Restart; add 0.1 M NaOH dropwise; keep pH 6.0–6.6
No solid after hydrothermal	pH too low / insufficient coordination	Adjust closer to pH 6.3; extend heating to 18 h if needed
XRD shows hydroxide/oxide	Conditions favor hydroxide/oxide formation	Lower pH target, reduce temperature to 100–110 °C, or shorten time

Record for every batch: Ni salt used, masses, pH after adjustment, temperature, time, mass after drying, and observations (color/precipitate/crystals).