Here's a modern sleek color palette with color names, hex codes, and descriptions for the mentioned purposes:

1. Primary:
   - Color Name: Midnight Blue
   - Hex Code: 
                            
                            #2c3e50
                        
   - Description: A deep and sophisticated blue for primary elements.

2. Secondary:
   - Color Name: Silver Grey
   - Hex Code: 
                            
                            #bdc3c7
                        
   - Description: A neutral and versatile grey for secondary elements.

3. Accent:
   - Color Name: Teal
   - Hex Code: 
                            
                            #1abc9c
                        
   - Description: A vibrant and refreshing teal for accentuating elements.

4. Dark:
   - Color Name: Charcoal
   - Hex Code: 
                            
                            #34495e
                        
   - Description: A rich and deep charcoal for dark backgrounds or elements.

5. Positive:
   - Color Name: Emerald
   - Hex Code: 
                            
                            #2ecc71
                        
   - Description: A lively and positive green for highlighting positive elements.

6. Negative:
   - Color Name: Garnet
   - Hex Code: 
                            
                            #c0392b
                        
   - Description: A bold and intense red for indicating negative elements.

7. Info:
   - Color Name: Steel Blue
   - Hex Code: 
                            
                            #4682b4
                        
   - Description: A cool and calm blue for conveying informational elements.

8. Warning:
   - Color Name: Sunflower
   - Hex Code: 
                            
                            #f1c40f
                        
   - Description: A bright and attention-grabbing yellow for warning or alert elements.

This color palette offers a balance of sophistication, vibrancy, and clarity, making it suitable for modern sleek designs with distinct purposes.